gecko-dev/widget/GfxInfoBase.cpp

/* vim: se cin sw=2 ts=2 et : */
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/ArrayUtils.h"

#include "GfxInfoBase.h"

#include "GfxInfoWebGL.h"
#include "GfxDriverInfo.h"
#include "nsCOMPtr.h"
#include "nsCOMArray.h"
#include "nsAutoPtr.h"
#include "nsString.h"
#include "nsUnicharUtils.h"
#include "nsVersionComparator.h"
#include "mozilla/Services.h"
#include "mozilla/Observer.h"
#include "nsIObserver.h"
#include "nsIObserverService.h"
#include "nsIDOMElement.h"
#include "nsIDOMHTMLCollection.h"
#include "nsIDOMNode.h"
#include "nsIDOMNodeList.h"
#include "nsTArray.h"
#include "nsXULAppAPI.h"
#include "nsIXULAppInfo.h"
#include "mozilla/Preferences.h"
#include "mozilla/dom/ContentChild.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/Logging.h"
#include "gfxPrefs.h"
#include "gfxPlatform.h"

#if defined(MOZ_CRASHREPORTER)
#include "nsExceptionHandler.h"
#endif

using namespace mozilla::widget;
using namespace mozilla;
using mozilla::MutexAutoLock;

nsTArray<GfxDriverInfo>* GfxInfoBase::mDriverInfo;
bool GfxInfoBase::mDriverInfoObserverInitialized;

// Observes for shutdown so that the child GfxDriverInfo list is freed.
class ShutdownObserver : public nsIObserver
{
  virtual ~ShutdownObserver() {}

public:
  ShutdownObserver() {}

  NS_DECL_ISUPPORTS

  NS_IMETHOD Observe(nsISupports *subject, const char *aTopic,
                     const char16_t *aData) override
  {
    MOZ_ASSERT(strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0);

    delete GfxInfoBase::mDriverInfo;
    GfxInfoBase::mDriverInfo = nullptr;

    for (uint32_t i = 0; i < DeviceFamilyMax; i++)
      delete GfxDriverInfo::mDeviceFamilies[i];

    for (uint32_t i = 0; i < DeviceVendorMax; i++)
      delete GfxDriverInfo::mDeviceVendors[i];

    return NS_OK;
  }
};

NS_IMPL_ISUPPORTS(ShutdownObserver, nsIObserver)

void InitGfxDriverInfoShutdownObserver()
{
  if (GfxInfoBase::mDriverInfoObserverInitialized)
    return;

  GfxInfoBase::mDriverInfoObserverInitialized = true;

  nsCOMPtr<nsIObserverService> observerService = services::GetObserverService();
  if (!observerService) {
    NS_WARNING("Could not get observer service!");
    return;
  }

  ShutdownObserver *obs = new ShutdownObserver();
  observerService->AddObserver(obs, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
}

using namespace mozilla::widget;
using namespace mozilla::gfx;
using namespace mozilla;

NS_IMPL_ISUPPORTS(GfxInfoBase, nsIGfxInfo, nsIObserver, nsISupportsWeakReference)

#define BLACKLIST_PREF_BRANCH "gfx.blacklist."
#define SUGGESTED_VERSION_PREF BLACKLIST_PREF_BRANCH "suggested-driver-version"
#define BLACKLIST_ENTRY_TAG_NAME "gfxBlacklistEntry"

static const char*
GetPrefNameForFeature(int32_t aFeature)
{
  const char* name = nullptr;
  switch(aFeature) {
    case nsIGfxInfo::FEATURE_DIRECT2D:
      name = BLACKLIST_PREF_BRANCH "direct2d";
      break;
    case nsIGfxInfo::FEATURE_DIRECT3D_9_LAYERS:
      name = BLACKLIST_PREF_BRANCH "layers.direct3d9";
      break;
    case nsIGfxInfo::FEATURE_DIRECT3D_10_LAYERS:
      name = BLACKLIST_PREF_BRANCH "layers.direct3d10";
      break;
    case nsIGfxInfo::FEATURE_DIRECT3D_10_1_LAYERS:
      name = BLACKLIST_PREF_BRANCH "layers.direct3d10-1";
      break;
    case nsIGfxInfo::FEATURE_DIRECT3D_11_LAYERS:
      name = BLACKLIST_PREF_BRANCH "layers.direct3d11";
      break;
    case nsIGfxInfo::FEATURE_DIRECT3D_11_ANGLE:
      name = BLACKLIST_PREF_BRANCH "direct3d11angle";
      break;
    case nsIGfxInfo::FEATURE_HARDWARE_VIDEO_DECODING:
      name = BLACKLIST_PREF_BRANCH "hardwarevideodecoding";
      break;
    case nsIGfxInfo::FEATURE_OPENGL_LAYERS:
      name = BLACKLIST_PREF_BRANCH "layers.opengl";
      break;
    case nsIGfxInfo::FEATURE_WEBGL_OPENGL:
      name = BLACKLIST_PREF_BRANCH "webgl.opengl";
      break;
    case nsIGfxInfo::FEATURE_WEBGL_ANGLE:
      name = BLACKLIST_PREF_BRANCH "webgl.angle";
      break;
    case nsIGfxInfo::FEATURE_WEBGL_MSAA:
      name = BLACKLIST_PREF_BRANCH "webgl.msaa";
      break;
    case nsIGfxInfo::FEATURE_STAGEFRIGHT:
      name = BLACKLIST_PREF_BRANCH "stagefright";
      break;
    case nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION:
      name = BLACKLIST_PREF_BRANCH "webrtc.hw.acceleration";
      break;
    case nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION_ENCODE:
      name = BLACKLIST_PREF_BRANCH "webrtc.hw.acceleration.encode";
      break;
    case nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION_DECODE:
      name = BLACKLIST_PREF_BRANCH "webrtc.hw.acceleration.decode";
      break;
    case nsIGfxInfo::FEATURE_CANVAS2D_ACCELERATION:
      name = BLACKLIST_PREF_BRANCH "canvas2d.acceleration";
      break;
    case nsIGfxInfo::FEATURE_VP8_HW_DECODE:
    case nsIGfxInfo::FEATURE_VP9_HW_DECODE:
      // We don't provide prefs for this features.
      break;
    default:
      MOZ_ASSERT_UNREACHABLE("Unexpected nsIGfxInfo feature?!");
      break;
  }

  return name;
}

// Returns the value of the pref for the relevant feature in aValue.
// If the pref doesn't exist, aValue is not touched, and returns false.
static bool
GetPrefValueForFeature(int32_t aFeature, int32_t& aValue)
{
  const char *prefname = GetPrefNameForFeature(aFeature);
  if (!prefname)
    return false;

  aValue = nsIGfxInfo::FEATURE_STATUS_UNKNOWN;
  return NS_SUCCEEDED(Preferences::GetInt(prefname, &aValue));
}

static void
SetPrefValueForFeature(int32_t aFeature, int32_t aValue)
{
  const char *prefname = GetPrefNameForFeature(aFeature);
  if (!prefname)
    return;

  Preferences::SetInt(prefname, aValue);
}

static void
RemovePrefForFeature(int32_t aFeature)
{
  const char *prefname = GetPrefNameForFeature(aFeature);
  if (!prefname)
    return;

  Preferences::ClearUser(prefname);
}

static bool
GetPrefValueForDriverVersion(nsCString& aVersion)
{
  return NS_SUCCEEDED(Preferences::GetCString(SUGGESTED_VERSION_PREF,
                                              &aVersion));
}

static void
SetPrefValueForDriverVersion(const nsAString& aVersion)
{
  Preferences::SetString(SUGGESTED_VERSION_PREF, aVersion);
}

static void
RemovePrefForDriverVersion()
{
  Preferences::ClearUser(SUGGESTED_VERSION_PREF);
}

// <foo>Hello</foo> - "Hello" is stored as a child text node of the foo node.
static bool
BlacklistNodeToTextValue(nsIDOMNode *aBlacklistNode, nsAString& aValue)
{
  nsAutoString value;
  if (NS_FAILED(aBlacklistNode->GetTextContent(value)))
    return false;

  value.Trim(" \t\r\n");
  aValue = value;

  return true;
}

// <foo attr=Hello/> finds "Hello" if the aAttrName is "attr".
static bool
BlacklistAttrToTextValue(nsIDOMNode *aBlacklistNode,
                         const nsAString& aAttrName,
                         nsAString& aValue)
{
  nsCOMPtr<nsIDOMElement> element = do_QueryInterface(aBlacklistNode);
  if (!element) {
    return false;
  }

  nsAutoString value;
  if (NS_FAILED(element->GetAttribute(aAttrName, value))) {
    return false;
  }

  value.Trim(" \t\r\n");
  aValue = value;

  return true;
}


static OperatingSystem
BlacklistOSToOperatingSystem(const nsAString& os)
{
  if (os.EqualsLiteral("WINNT 5.1"))
    return DRIVER_OS_WINDOWS_XP;
  else if (os.EqualsLiteral("WINNT 5.2"))
    return DRIVER_OS_WINDOWS_SERVER_2003;
  else if (os.EqualsLiteral("WINNT 6.0"))
    return DRIVER_OS_WINDOWS_VISTA;
  else if (os.EqualsLiteral("WINNT 6.1"))
    return DRIVER_OS_WINDOWS_7;
  else if (os.EqualsLiteral("WINNT 6.2"))
    return DRIVER_OS_WINDOWS_8;
  else if (os.EqualsLiteral("WINNT 6.3"))
    return DRIVER_OS_WINDOWS_8_1;
  else if (os.EqualsLiteral("WINNT 10.0"))
    return DRIVER_OS_WINDOWS_10;
  else if (os.EqualsLiteral("Linux"))
    return DRIVER_OS_LINUX;
  else if (os.EqualsLiteral("Darwin 9"))
    return DRIVER_OS_OS_X_10_5;
  else if (os.EqualsLiteral("Darwin 10"))
    return DRIVER_OS_OS_X_10_6;
  else if (os.EqualsLiteral("Darwin 11"))
    return DRIVER_OS_OS_X_10_7;
  else if (os.EqualsLiteral("Darwin 12"))
    return DRIVER_OS_OS_X_10_8;
  else if (os.EqualsLiteral("Darwin 13"))
    return DRIVER_OS_OS_X_10_9;
  else if (os.EqualsLiteral("Darwin 14"))
    return DRIVER_OS_OS_X_10_10;
  else if (os.EqualsLiteral("Darwin 15"))
    return DRIVER_OS_OS_X_10_11;
  else if (os.EqualsLiteral("Android"))
    return DRIVER_OS_ANDROID;
  else if (os.EqualsLiteral("All"))
    return DRIVER_OS_ALL;

  return DRIVER_OS_UNKNOWN;
}

static GfxDeviceFamily*
BlacklistDevicesToDeviceFamily(nsIDOMHTMLCollection* aDevices)
{
  uint32_t length;
  if (NS_FAILED(aDevices->GetLength(&length)))
    return nullptr;

  // For each <device>, get its device ID, and return a freshly-allocated
  // GfxDeviceFamily with the contents of that array.
  GfxDeviceFamily* deviceIds = new GfxDeviceFamily;

  for (uint32_t i = 0; i < length; ++i) {
    nsCOMPtr<nsIDOMNode> node;
    if (NS_FAILED(aDevices->Item(i, getter_AddRefs(node))) || !node)
      continue;

    nsAutoString deviceValue;
    if (!BlacklistNodeToTextValue(node, deviceValue))
      continue;

    deviceIds->AppendElement(deviceValue);
  }

  return deviceIds;
}

static int32_t
BlacklistFeatureToGfxFeature(const nsAString& aFeature)
{
  MOZ_ASSERT(!aFeature.IsEmpty());
  if (aFeature.EqualsLiteral("DIRECT2D"))
    return nsIGfxInfo::FEATURE_DIRECT2D;
  else if (aFeature.EqualsLiteral("DIRECT3D_9_LAYERS"))
    return nsIGfxInfo::FEATURE_DIRECT3D_9_LAYERS;
  else if (aFeature.EqualsLiteral("DIRECT3D_10_LAYERS"))
    return nsIGfxInfo::FEATURE_DIRECT3D_10_LAYERS;
  else if (aFeature.EqualsLiteral("DIRECT3D_10_1_LAYERS"))
    return nsIGfxInfo::FEATURE_DIRECT3D_10_1_LAYERS;
  else if (aFeature.EqualsLiteral("DIRECT3D_11_LAYERS"))
    return nsIGfxInfo::FEATURE_DIRECT3D_11_LAYERS;
  else if (aFeature.EqualsLiteral("DIRECT3D_11_ANGLE"))
    return nsIGfxInfo::FEATURE_DIRECT3D_11_ANGLE;
  else if (aFeature.EqualsLiteral("HARDWARE_VIDEO_DECODING"))
    return nsIGfxInfo::FEATURE_HARDWARE_VIDEO_DECODING;
  else if (aFeature.EqualsLiteral("OPENGL_LAYERS"))
    return nsIGfxInfo::FEATURE_OPENGL_LAYERS;
  else if (aFeature.EqualsLiteral("WEBGL_OPENGL"))
    return nsIGfxInfo::FEATURE_WEBGL_OPENGL;
  else if (aFeature.EqualsLiteral("WEBGL_ANGLE"))
    return nsIGfxInfo::FEATURE_WEBGL_ANGLE;
  else if (aFeature.EqualsLiteral("WEBGL_MSAA"))
    return nsIGfxInfo::FEATURE_WEBGL_MSAA;
  else if (aFeature.EqualsLiteral("STAGEFRIGHT"))
    return nsIGfxInfo::FEATURE_STAGEFRIGHT;
  else if (aFeature.EqualsLiteral("WEBRTC_HW_ACCELERATION_ENCODE"))
    return nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION_ENCODE;
  else if (aFeature.EqualsLiteral("WEBRTC_HW_ACCELERATION_DECODE"))
    return nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION_DECODE;
  else if (aFeature.EqualsLiteral("WEBRTC_HW_ACCELERATION"))
    return nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION;
  else if (aFeature.EqualsLiteral("CANVAS2D_ACCELERATION"))
      return nsIGfxInfo::FEATURE_CANVAS2D_ACCELERATION;

  // If we don't recognize the feature, it may be new, and something
  // this version doesn't understand.  So, nothing to do.  This is
  // different from feature not being specified at all, in which case
  // this method should not get called and we should continue with the
  // "all features" blocklisting.
  return -1;
}

static int32_t
BlacklistFeatureStatusToGfxFeatureStatus(const nsAString& aStatus)
{
  if (aStatus.EqualsLiteral("STATUS_OK"))
    return nsIGfxInfo::FEATURE_STATUS_OK;
  else if (aStatus.EqualsLiteral("BLOCKED_DRIVER_VERSION"))
    return nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION;
  else if (aStatus.EqualsLiteral("BLOCKED_DEVICE"))
    return nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
  else if (aStatus.EqualsLiteral("DISCOURAGED"))
    return nsIGfxInfo::FEATURE_DISCOURAGED;
  else if (aStatus.EqualsLiteral("BLOCKED_OS_VERSION"))
    return nsIGfxInfo::FEATURE_BLOCKED_OS_VERSION;

  // Do not allow it to set STATUS_UNKNOWN.  Also, we are not
  // expecting the "mismatch" status showing up here.

  return nsIGfxInfo::FEATURE_STATUS_OK;
}

static VersionComparisonOp
BlacklistComparatorToComparisonOp(const nsAString& op)
{
  if (op.EqualsLiteral("LESS_THAN"))
    return DRIVER_LESS_THAN;
  else if (op.EqualsLiteral("LESS_THAN_OR_EQUAL"))
    return DRIVER_LESS_THAN_OR_EQUAL;
  else if (op.EqualsLiteral("GREATER_THAN"))
    return DRIVER_GREATER_THAN;
  else if (op.EqualsLiteral("GREATER_THAN_OR_EQUAL"))
    return DRIVER_GREATER_THAN_OR_EQUAL;
  else if (op.EqualsLiteral("EQUAL"))
    return DRIVER_EQUAL;
  else if (op.EqualsLiteral("NOT_EQUAL"))
    return DRIVER_NOT_EQUAL;
  else if (op.EqualsLiteral("BETWEEN_EXCLUSIVE"))
    return DRIVER_BETWEEN_EXCLUSIVE;
  else if (op.EqualsLiteral("BETWEEN_INCLUSIVE"))
    return DRIVER_BETWEEN_INCLUSIVE;
  else if (op.EqualsLiteral("BETWEEN_INCLUSIVE_START"))
    return DRIVER_BETWEEN_INCLUSIVE_START;

  return DRIVER_COMPARISON_IGNORED;
}

// Arbitrarily returns the first |tagname| child of |element|.
static bool
BlacklistNodeGetChildByName(nsIDOMElement *element,
                            const nsAString& tagname,
                            nsIDOMNode** firstchild)
{
  nsCOMPtr<nsIDOMHTMLCollection> nodelist;
  if (NS_FAILED(element->GetElementsByTagName(tagname,
                                              getter_AddRefs(nodelist))) ||
      !nodelist) {
    return false;
  }

  nsCOMPtr<nsIDOMNode> node;
  if (NS_FAILED(nodelist->Item(0, getter_AddRefs(node))) || !node)
    return false;

  node.forget(firstchild);
  return true;
}

/*

<gfxBlacklistEntry>
  <os>WINNT 6.0</os>
  <vendor>0x8086</vendor>
  <devices>
    <device>0x2582</device>
    <device>0x2782</device>
  </devices>
  <feature> DIRECT3D_10_LAYERS </feature>
  <featureStatus> BLOCKED_DRIVER_VERSION </featureStatus>
  <driverVersion> 8.52.322.2202 </driverVersion>
  <driverVersionComparator> LESS_THAN_OR_EQUAL </driverVersionComparator>
</gfxBlacklistEntry>

*/
static bool
BlacklistEntryToDriverInfo(nsIDOMNode* aBlacklistEntry,
                           GfxDriverInfo& aDriverInfo)
{
  nsAutoString nodename;
  if (NS_FAILED(aBlacklistEntry->GetNodeName(nodename)) ||
      nodename != NS_LITERAL_STRING(BLACKLIST_ENTRY_TAG_NAME)) {
    return false;
  }

  nsCOMPtr<nsIDOMElement> element = do_QueryInterface(aBlacklistEntry);
  if (!element)
    return false;

  nsCOMPtr<nsIDOMNode> dataNode;
  nsAutoString dataValue;

  // If we get an application version to be zero, something is not working
  // and we are not going to bother checking the blocklist versions.
  // See TestGfxWidgets.cpp for how version comparison works.
  // <versionRange minVersion="42.0a1" maxVersion="45.0"></versionRange>
  static mozilla::Version zeroV("0");
  static mozilla::Version appV(GfxInfoBase::GetApplicationVersion().get());
  if (appV <= zeroV) {
      gfxCriticalErrorOnce(gfxCriticalError::DefaultOptions(false)) << "Invalid application version " << GfxInfoBase::GetApplicationVersion().get();
  } else if (BlacklistNodeGetChildByName(element,
                                         NS_LITERAL_STRING("versionRange"),
                                         getter_AddRefs(dataNode))) {
    if (BlacklistAttrToTextValue(dataNode,
                                 NS_LITERAL_STRING("minVersion"),
                                 dataValue)) {
      mozilla::Version minV(NS_ConvertUTF16toUTF8(dataValue).get());
      if (minV > zeroV && appV < minV) {
        // The version of the application is less than the minimal version
        // this blocklist entry applies to, so we can just ignore it by
        // returning false and letting the caller deal with it.
        return false;
      }
    }

    if (BlacklistAttrToTextValue(dataNode,
                                 NS_LITERAL_STRING("maxVersion"),
                                 dataValue)) {
      mozilla::Version maxV(NS_ConvertUTF16toUTF8(dataValue).get());
      if (maxV > zeroV && appV > maxV) {
        // The version of the application is more than the maximal version
        // this blocklist entry applies to, so we can just ignore it by
        // returning false and letting the caller deal with it.
        return false;
      }
    }
  }

  // <os>WINNT 6.0</os>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("os"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mOperatingSystem = BlacklistOSToOperatingSystem(dataValue);
  }

  // <osversion>14</osversion> currently only used for Android
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("osversion"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mOperatingSystemVersion = strtoul(NS_LossyConvertUTF16toASCII(dataValue).get(),
                                                  nullptr, 10);
  }

  // <vendor>0x8086</vendor>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("vendor"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mAdapterVendor = dataValue;
  }

  // <devices>
  //   <device>0x2582</device>
  //   <device>0x2782</device>
  // </devices>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("devices"),
                                  getter_AddRefs(dataNode))) {
    nsCOMPtr<nsIDOMElement> devicesElement = do_QueryInterface(dataNode);
    if (devicesElement) {

      // Get only the <device> nodes, because BlacklistDevicesToDeviceFamily
      // assumes it is passed no other nodes.
      nsCOMPtr<nsIDOMHTMLCollection> devices;
      if (NS_SUCCEEDED(devicesElement->GetElementsByTagName(NS_LITERAL_STRING("device"),
                                                            getter_AddRefs(devices)))) {
        GfxDeviceFamily* deviceIds = BlacklistDevicesToDeviceFamily(devices);
        if (deviceIds) {
          // Get GfxDriverInfo to adopt the devices array we created.
          aDriverInfo.mDeleteDevices = true;
          aDriverInfo.mDevices = deviceIds;
        }
      }
    }
  }

  // <feature> DIRECT3D_10_LAYERS </feature>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("feature"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mFeature = BlacklistFeatureToGfxFeature(dataValue);
    if (aDriverInfo.mFeature < 0) {
      // If we don't recognize the feature, we do not want to proceed.
      gfxWarning() << "Unrecognized feature " << NS_ConvertUTF16toUTF8(dataValue).get();
      return false;
    }
  }

  // <featureStatus> BLOCKED_DRIVER_VERSION </featureStatus>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("featureStatus"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mFeatureStatus = BlacklistFeatureStatusToGfxFeatureStatus(dataValue);
  }

  // <driverVersion> 8.52.322.2202 </driverVersion>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("driverVersion"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    uint64_t version;
    if (ParseDriverVersion(dataValue, &version))
      aDriverInfo.mDriverVersion = version;
  }

  // <driverVersionMax> 8.52.322.2202 </driverVersionMax>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("driverVersionMax"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    uint64_t version;
    if (ParseDriverVersion(dataValue, &version))
      aDriverInfo.mDriverVersionMax = version;
  }

  // <driverVersionComparator> LESS_THAN_OR_EQUAL </driverVersionComparator>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("driverVersionComparator"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mComparisonOp = BlacklistComparatorToComparisonOp(dataValue);
  }

  // <model>foo</model>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("model"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mModel = dataValue;
  }
  // <product>foo</product>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("product"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mProduct = dataValue;
  }
  // <manufacturer>foo</manufacturer>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("manufacturer"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mManufacturer = dataValue;
  }
  // <hardware>foo</hardware>
  if (BlacklistNodeGetChildByName(element, NS_LITERAL_STRING("hardware"),
                                  getter_AddRefs(dataNode))) {
    BlacklistNodeToTextValue(dataNode, dataValue);
    aDriverInfo.mHardware = dataValue;
  }

  // We explicitly ignore unknown elements.

  return true;
}

static void
BlacklistEntriesToDriverInfo(nsIDOMHTMLCollection* aBlacklistEntries,
                             nsTArray<GfxDriverInfo>& aDriverInfo)
{
  uint32_t length;
  if (NS_FAILED(aBlacklistEntries->GetLength(&length)))
    return;

  aDriverInfo.Clear();
  aDriverInfo.SetLength(length);
  for (uint32_t i = 0; i < length; ++i) {
    nsCOMPtr<nsIDOMNode> blacklistEntry;
    if (NS_SUCCEEDED(aBlacklistEntries->Item(i,
                                             getter_AddRefs(blacklistEntry))) &&
        blacklistEntry) {
      GfxDriverInfo di;
      if (BlacklistEntryToDriverInfo(blacklistEntry, di)) {
        aDriverInfo[i] = di;
        // Prevent di falling out of scope from destroying the devices.
        di.mDeleteDevices = false;
      }
    }
  }
}

NS_IMETHODIMP
GfxInfoBase::Observe(nsISupports* aSubject, const char* aTopic,
                     const char16_t* aData)
{
  if (strcmp(aTopic, "blocklist-data-gfxItems") == 0) {
    nsCOMPtr<nsIDOMElement> gfxItems = do_QueryInterface(aSubject);
    if (gfxItems) {
      nsCOMPtr<nsIDOMHTMLCollection> blacklistEntries;
      if (NS_SUCCEEDED(gfxItems->
            GetElementsByTagName(NS_LITERAL_STRING(BLACKLIST_ENTRY_TAG_NAME),
                                 getter_AddRefs(blacklistEntries))) &&
          blacklistEntries)
      {
        nsTArray<GfxDriverInfo> driverInfo;
        BlacklistEntriesToDriverInfo(blacklistEntries, driverInfo);
        EvaluateDownloadedBlacklist(driverInfo);
      }
    }
  }

  return NS_OK;
}

GfxInfoBase::GfxInfoBase()
    : mMutex("GfxInfoBase")
{
}

GfxInfoBase::~GfxInfoBase()
{
}

nsresult
GfxInfoBase::Init()
{
  InitGfxDriverInfoShutdownObserver();
  gfxPrefs::GetSingleton();

  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
  if (os) {
    os->AddObserver(this, "blocklist-data-gfxItems", true);
  }

  return NS_OK;
}

NS_IMETHODIMP
GfxInfoBase::GetFeatureStatus(int32_t aFeature, int32_t* aStatus)
{
  int32_t blocklistAll = gfxPrefs::BlocklistAll();
  if (blocklistAll > 0) {
    gfxCriticalErrorOnce(gfxCriticalError::DefaultOptions(false)) << "Forcing blocklisting all features";
    *aStatus = FEATURE_BLOCKED_DEVICE;
    return NS_OK;
  } else if (blocklistAll < 0) {
    gfxCriticalErrorOnce(gfxCriticalError::DefaultOptions(false)) << "Ignoring any feature blocklisting.";
    *aStatus = FEATURE_STATUS_OK;
    return NS_OK;
  }

  if (GetPrefValueForFeature(aFeature, *aStatus))
    return NS_OK;

  if (XRE_IsContentProcess()) {
      // Delegate to the parent process.
      mozilla::dom::ContentChild* cc = mozilla::dom::ContentChild::GetSingleton();
      bool success;
      cc->SendGetGraphicsFeatureStatus(aFeature, aStatus, &success);
      return success ? NS_OK : NS_ERROR_FAILURE;
  }

  nsString version;
  nsTArray<GfxDriverInfo> driverInfo;
  return GetFeatureStatusImpl(aFeature, aStatus, version, driverInfo);
}

int32_t
GfxInfoBase::FindBlocklistedDeviceInList(const nsTArray<GfxDriverInfo>& info,
                                         nsAString& aSuggestedVersion,
                                         int32_t aFeature,
                                         OperatingSystem os)
{
  int32_t status = nsIGfxInfo::FEATURE_STATUS_UNKNOWN;

  uint32_t i = 0;
  for (; i < info.Length(); i++) {
    // Do the operating system check first, no point in getting the driver
    // info if we won't need to use it.  If the OS of the system we are running
    // on is unknown, we still let DRIVER_OS_ALL catch and disable it; 
    // if the OS of the downloadable entry is unknown, we skip the entry
    // as invalid.
    if (info[i].mOperatingSystem == DRIVER_OS_UNKNOWN ||
        (info[i].mOperatingSystem != DRIVER_OS_ALL &&
         info[i].mOperatingSystem != os))
    {
      continue;
    }

    if (info[i].mOperatingSystemVersion && info[i].mOperatingSystemVersion != OperatingSystemVersion()) {
        continue;
    }

    // XXX: it would be better not to do this everytime round the loop
    nsAutoString adapterVendorID;
    nsAutoString adapterDeviceID;
    nsAutoString adapterDriverVersionString;
    if (info[i].mGpu2) {
      if (NS_FAILED(GetAdapterVendorID2(adapterVendorID)) ||
          NS_FAILED(GetAdapterDeviceID2(adapterDeviceID)) ||
          NS_FAILED(GetAdapterDriverVersion2(adapterDriverVersionString)))
      {
        return 0;
      }
    } else {
      if (NS_FAILED(GetAdapterVendorID(adapterVendorID)) ||
          NS_FAILED(GetAdapterDeviceID(adapterDeviceID)) ||
          NS_FAILED(GetAdapterDriverVersion(adapterDriverVersionString)))
      {
        return 0;
      }
    }

#if defined(XP_WIN) || defined(ANDROID)
    uint64_t driverVersion;
    ParseDriverVersion(adapterDriverVersionString, &driverVersion);
#endif

    if (!info[i].mAdapterVendor.Equals(GfxDriverInfo::GetDeviceVendor(VendorAll), nsCaseInsensitiveStringComparator()) &&
        !info[i].mAdapterVendor.Equals(adapterVendorID, nsCaseInsensitiveStringComparator())) {
      continue;
    }

    if (info[i].mDevices != GfxDriverInfo::allDevices && info[i].mDevices->Length()) {
        bool deviceMatches = false;
        for (uint32_t j = 0; j < info[i].mDevices->Length(); j++) {
            if ((*info[i].mDevices)[j].Equals(adapterDeviceID, nsCaseInsensitiveStringComparator())) {
                deviceMatches = true;
                break;
            }
        }

        if (!deviceMatches) {
            continue;
        }
    }

    bool match = false;

    if (!info[i].mHardware.IsEmpty() && !info[i].mHardware.Equals(Hardware())) {
        continue;
    }
    if (!info[i].mModel.IsEmpty() && !info[i].mModel.Equals(Model())) {
        continue;
    }
    if (!info[i].mProduct.IsEmpty() && !info[i].mProduct.Equals(Product())) {
        continue;
    }
    if (!info[i].mManufacturer.IsEmpty() && !info[i].mManufacturer.Equals(Manufacturer())) {
        continue;
    }

#if defined(XP_WIN) || defined(ANDROID)
    switch (info[i].mComparisonOp) {
    case DRIVER_LESS_THAN:
      match = driverVersion < info[i].mDriverVersion;
      break;
    case DRIVER_LESS_THAN_OR_EQUAL:
      match = driverVersion <= info[i].mDriverVersion;
      break;
    case DRIVER_GREATER_THAN:
      match = driverVersion > info[i].mDriverVersion;
      break;
    case DRIVER_GREATER_THAN_OR_EQUAL:
      match = driverVersion >= info[i].mDriverVersion;
      break;
    case DRIVER_EQUAL:
      match = driverVersion == info[i].mDriverVersion;
      break;
    case DRIVER_NOT_EQUAL:
      match = driverVersion != info[i].mDriverVersion;
      break;
    case DRIVER_BETWEEN_EXCLUSIVE:
      match = driverVersion > info[i].mDriverVersion && driverVersion < info[i].mDriverVersionMax;
      break;
    case DRIVER_BETWEEN_INCLUSIVE:
      match = driverVersion >= info[i].mDriverVersion && driverVersion <= info[i].mDriverVersionMax;
      break;
    case DRIVER_BETWEEN_INCLUSIVE_START:
      match = driverVersion >= info[i].mDriverVersion && driverVersion < info[i].mDriverVersionMax;
      break;
    case DRIVER_COMPARISON_IGNORED:
      // We don't have a comparison op, so we match everything.
      match = true;
      break;
    default:
      NS_WARNING("Bogus op in GfxDriverInfo");
      break;
    }
#else
    // We don't care what driver version it was. We only check OS version and if
    // the device matches.
    match = true;
#endif

    if (match || info[i].mDriverVersion == GfxDriverInfo::allDriverVersions) {
      if (info[i].mFeature == GfxDriverInfo::allFeatures ||
          info[i].mFeature == aFeature)
      {
        status = info[i].mFeatureStatus;
        break;
      }
    }
  }

#if defined(XP_WIN)
  // As a very special case, we block D2D on machines with an NVidia 310M GPU
  // as either the primary or secondary adapter.  D2D is also blocked when the
  // NV 310M is the primary adapter (using the standard blocklisting mechanism).
  // If the primary GPU already matched something in the blocklist then we
  // ignore this special rule.  See bug 1008759.
  if (status == nsIGfxInfo::FEATURE_STATUS_UNKNOWN &&
    (aFeature == nsIGfxInfo::FEATURE_DIRECT2D)) {
    nsAutoString adapterVendorID2;
    nsAutoString adapterDeviceID2;
    if ((!NS_FAILED(GetAdapterVendorID2(adapterVendorID2))) &&
      (!NS_FAILED(GetAdapterDeviceID2(adapterDeviceID2))))
    {
      nsAString &nvVendorID = (nsAString &)GfxDriverInfo::GetDeviceVendor(VendorNVIDIA);
      const nsString nv310mDeviceId = NS_LITERAL_STRING("0x0A70");
      if (nvVendorID.Equals(adapterVendorID2, nsCaseInsensitiveStringComparator()) &&
        nv310mDeviceId.Equals(adapterDeviceID2, nsCaseInsensitiveStringComparator())) {
        status = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
      }
    }
  }

  // Depends on Windows driver versioning. We don't pass a GfxDriverInfo object
  // back to the Windows handler, so we must handle this here.
  if (status == FEATURE_BLOCKED_DRIVER_VERSION) {
    if (info[i].mSuggestedVersion) {
        aSuggestedVersion.AppendPrintf("%s", info[i].mSuggestedVersion);
    } else if (info[i].mComparisonOp == DRIVER_LESS_THAN &&
               info[i].mDriverVersion != GfxDriverInfo::allDriverVersions)
    {
        aSuggestedVersion.AppendPrintf("%lld.%lld.%lld.%lld",
                                      (info[i].mDriverVersion & 0xffff000000000000) >> 48,
                                      (info[i].mDriverVersion & 0x0000ffff00000000) >> 32,
                                      (info[i].mDriverVersion & 0x00000000ffff0000) >> 16,
                                      (info[i].mDriverVersion & 0x000000000000ffff));
    }
  }
#endif

  return status;
}

nsresult
GfxInfoBase::GetFeatureStatusImpl(int32_t aFeature,
                                  int32_t* aStatus,
                                  nsAString& aSuggestedVersion,
                                  const nsTArray<GfxDriverInfo>& aDriverInfo,
                                  OperatingSystem* aOS /* = nullptr */)
{
  if (aFeature <= 0) {
    gfxWarning() << "Invalid feature <= 0";
    return NS_OK;
  }

  if (*aStatus != nsIGfxInfo::FEATURE_STATUS_UNKNOWN) {
    // Terminate now with the status determined by the derived type (OS-specific
    // code).
    return NS_OK;
  }

  // If an operating system was provided by the derived GetFeatureStatusImpl,
  // grab it here. Otherwise, the OS is unknown.
  OperatingSystem os = DRIVER_OS_UNKNOWN;
  if (aOS)
    os = *aOS;

  nsAutoString adapterVendorID;
  nsAutoString adapterDeviceID;
  nsAutoString adapterDriverVersionString;
  if (NS_FAILED(GetAdapterVendorID(adapterVendorID)) ||
      NS_FAILED(GetAdapterDeviceID(adapterDeviceID)) ||
      NS_FAILED(GetAdapterDriverVersion(adapterDriverVersionString)))
  {
    return NS_OK;
  }

  // Check if the device is blocked from the downloaded blocklist. If not, check
  // the static list after that. This order is used so that we can later escape
  // out of static blocks (i.e. if we were wrong or something was patched, we
  // can back out our static block without doing a release).
  int32_t status;
  if (aDriverInfo.Length()) {
    status = FindBlocklistedDeviceInList(aDriverInfo, aSuggestedVersion, aFeature, os);
  } else {
    if (!mDriverInfo) {
      mDriverInfo = new nsTArray<GfxDriverInfo>();
    }
    status = FindBlocklistedDeviceInList(GetGfxDriverInfo(), aSuggestedVersion, aFeature, os);
  }

  // It's now done being processed. It's safe to set the status to STATUS_OK.
  if (status == nsIGfxInfo::FEATURE_STATUS_UNKNOWN) {
    *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
  } else {
    *aStatus = status;
  }

  return NS_OK;
}

NS_IMETHODIMP
GfxInfoBase::GetFeatureSuggestedDriverVersion(int32_t aFeature,
                                              nsAString& aVersion)
{
  nsCString version;
  if (GetPrefValueForDriverVersion(version)) {
    aVersion = NS_ConvertASCIItoUTF16(version);
    return NS_OK;
  }

  int32_t status;
  nsTArray<GfxDriverInfo> driverInfo;
  return GetFeatureStatusImpl(aFeature, &status, aVersion, driverInfo);
}


NS_IMETHODIMP
GfxInfoBase::GetWebGLParameter(const nsAString& aParam,
                               nsAString& aResult)
{
  return GfxInfoWebGL::GetWebGLParameter(aParam, aResult);
}

void
GfxInfoBase::EvaluateDownloadedBlacklist(nsTArray<GfxDriverInfo>& aDriverInfo)
{
  int32_t features[] = {
    nsIGfxInfo::FEATURE_DIRECT2D,
    nsIGfxInfo::FEATURE_DIRECT3D_9_LAYERS,
    nsIGfxInfo::FEATURE_DIRECT3D_10_LAYERS,
    nsIGfxInfo::FEATURE_DIRECT3D_10_1_LAYERS,
    nsIGfxInfo::FEATURE_DIRECT3D_11_LAYERS,
    nsIGfxInfo::FEATURE_DIRECT3D_11_ANGLE,
    nsIGfxInfo::FEATURE_HARDWARE_VIDEO_DECODING,
    nsIGfxInfo::FEATURE_OPENGL_LAYERS,
    nsIGfxInfo::FEATURE_WEBGL_OPENGL,
    nsIGfxInfo::FEATURE_WEBGL_ANGLE,
    nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION_ENCODE,
    nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION_DECODE,
    nsIGfxInfo::FEATURE_WEBGL_MSAA,
    nsIGfxInfo::FEATURE_STAGEFRIGHT,
    nsIGfxInfo::FEATURE_WEBRTC_HW_ACCELERATION,
    nsIGfxInfo::FEATURE_CANVAS2D_ACCELERATION,
    0
  };

  // For every feature we know about, we evaluate whether this blacklist has a
  // non-STATUS_OK status. If it does, we set the pref we evaluate in
  // GetFeatureStatus above, so we don't need to hold on to this blacklist
  // anywhere permanent.
  int i = 0;
  while (features[i]) {
    int32_t status;
    nsAutoString suggestedVersion;
    if (NS_SUCCEEDED(GetFeatureStatusImpl(features[i], &status,
                                          suggestedVersion,
                                          aDriverInfo))) {
      switch (status) {
        default:
        case nsIGfxInfo::FEATURE_STATUS_OK:
          RemovePrefForFeature(features[i]);
          break;

        case nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION:
          if (!suggestedVersion.IsEmpty()) {
            SetPrefValueForDriverVersion(suggestedVersion);
          } else {
            RemovePrefForDriverVersion();
          }
          MOZ_FALLTHROUGH;

        case nsIGfxInfo::FEATURE_BLOCKED_MISMATCHED_VERSION:
        case nsIGfxInfo::FEATURE_BLOCKED_DEVICE:
        case nsIGfxInfo::FEATURE_DISCOURAGED:
        case nsIGfxInfo::FEATURE_BLOCKED_OS_VERSION:
          SetPrefValueForFeature(features[i], status);
          break;
      }
    }

    ++i;
  }
}

NS_IMETHODIMP_(void)
GfxInfoBase::LogFailure(const nsACString &failure)
{
  // gfxCriticalError has a mutex lock of its own, so we may not actually
  // need this lock. ::GetFailures() accesses the data but the LogForwarder
  // will not return the copy of the logs unless it can get the same lock
  // that gfxCriticalError uses.  Still, that is so much of an implementation
  // detail that it's nicer to just add an extra lock here and in ::GetFailures()
  MutexAutoLock lock(mMutex);

  // By default, gfxCriticalError asserts; make it not assert in this case.
  gfxCriticalError(CriticalLog::DefaultOptions(false)) << "(LF) " << failure.BeginReading();
}

/* XPConnect method of returning arrays is very ugly. Would not recommend. */
NS_IMETHODIMP GfxInfoBase::GetFailures(uint32_t* failureCount,
                                       int32_t** indices,
                                       char ***failures)
{
  MutexAutoLock lock(mMutex);

  NS_ENSURE_ARG_POINTER(failureCount);
  NS_ENSURE_ARG_POINTER(failures);

  *failures = nullptr;
  *failureCount = 0;

  // indices is "allowed" to be null, the caller may not care about them,
  // although calling from JS doesn't seem to get us there.
  if (indices) *indices = nullptr;

  LogForwarder* logForwarder = Factory::GetLogForwarder();
  if (!logForwarder) {
    return NS_ERROR_UNEXPECTED;
  }

  // There are two stirng copies in this method, starting with this one. We are
  // assuming this is not a big deal, as the size of the array should be small
  // and the strings in it should be small as well (the error messages in the
  // code.)  The second copy happens with the Clone() calls.  Technically,
  // we don't need the mutex lock after the StringVectorCopy() call.
  LoggingRecord loggedStrings = logForwarder->LoggingRecordCopy();
  *failureCount = loggedStrings.size();

  if (*failureCount != 0) {
    *failures = (char**)moz_xmalloc(*failureCount * sizeof(char*));
    if (!(*failures)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
    if (indices) {
      *indices = (int32_t*)moz_xmalloc(*failureCount * sizeof(int32_t));
      if (!(*indices)) {
        free(*failures);
        *failures = nullptr;
        return NS_ERROR_OUT_OF_MEMORY;
      }
    }

    /* copy over the failure messages into the array we just allocated */
    LoggingRecord::const_iterator it;
    uint32_t i=0;
    for(it = loggedStrings.begin() ; it != loggedStrings.end(); ++it, i++) {
      (*failures)[i] = (char*)nsMemory::Clone(Get<1>(*it).c_str(), Get<1>(*it).size() + 1);
      if (indices) (*indices)[i] = Get<0>(*it);

      if (!(*failures)[i]) {
        /* <sarcasm> I'm too afraid to use an inline function... </sarcasm> */
        NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(i, (*failures));
        *failureCount = i;
        return NS_ERROR_OUT_OF_MEMORY;
      }
    }
  }

  return NS_OK;
}

nsTArray<GfxInfoCollectorBase*> *sCollectors;

static void
InitCollectors()
{
  if (!sCollectors)
    sCollectors = new nsTArray<GfxInfoCollectorBase*>;
}

nsresult GfxInfoBase::GetInfo(JSContext* aCx, JS::MutableHandle<JS::Value> aResult)
{
  InitCollectors();
  InfoObject obj(aCx);

  for (uint32_t i = 0; i < sCollectors->Length(); i++) {
    (*sCollectors)[i]->GetInfo(obj);
  }

  // Some example property definitions
  // obj.DefineProperty("wordCacheSize", gfxTextRunWordCache::Count());
  // obj.DefineProperty("renderer", mRendererIDsString);
  // obj.DefineProperty("five", 5);

  if (!obj.mOk) {
    return NS_ERROR_FAILURE;
  }

  aResult.setObject(*obj.mObj);
  return NS_OK;
}

nsAutoCString gBaseAppVersion;

const nsCString&
GfxInfoBase::GetApplicationVersion()
{
  static bool versionInitialized = false;
  if (!versionInitialized) {
    // If we fail to get the version, we will not try again.
    versionInitialized = true;

    // Get the version from xpcom/system/nsIXULAppInfo.idl
    nsCOMPtr<nsIXULAppInfo> app = do_GetService("@mozilla.org/xre/app-info;1");
    if (app) {
      app->GetVersion(gBaseAppVersion);
    }
  }
  return gBaseAppVersion;
}

void
GfxInfoBase::AddCollector(GfxInfoCollectorBase* collector)
{
  InitCollectors();
  sCollectors->AppendElement(collector);
}

void
GfxInfoBase::RemoveCollector(GfxInfoCollectorBase* collector)
{
  InitCollectors();
  for (uint32_t i = 0; i < sCollectors->Length(); i++) {
    if ((*sCollectors)[i] == collector) {
      sCollectors->RemoveElementAt(i);
      break;
    }
  }
  if (sCollectors->IsEmpty()) {
    delete sCollectors;
    sCollectors = nullptr;
  }
}

NS_IMETHODIMP
GfxInfoBase::GetMonitors(JSContext* aCx, JS::MutableHandleValue aResult)
{
  JS::Rooted<JSObject*> array(aCx, JS_NewArrayObject(aCx, 0));

  nsresult rv = FindMonitors(aCx, array);
  if (NS_FAILED(rv)) {
    return rv;
  }

  aResult.setObject(*array);
  return NS_OK;
}

static const char*
GetLayersBackendName(layers::LayersBackend aBackend)
{
  switch (aBackend) {
    case layers::LayersBackend::LAYERS_NONE:
      return "none";
    case layers::LayersBackend::LAYERS_OPENGL:
      return "opengl";
    case layers::LayersBackend::LAYERS_D3D9:
      return "d3d9";
    case layers::LayersBackend::LAYERS_D3D11:
      return "d3d11";
    case layers::LayersBackend::LAYERS_CLIENT:
      return "client";
    case layers::LayersBackend::LAYERS_BASIC:
      return "basic";
    default:
      MOZ_ASSERT_UNREACHABLE("unknown layers backend");
      return "unknown";
  }
}

nsresult
GfxInfoBase::GetFeatures(JSContext* aCx, JS::MutableHandle<JS::Value> aOut)
{
  JS::Rooted<JSObject*> obj(aCx, JS_NewPlainObject(aCx));
  if (!obj) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  aOut.setObject(*obj);

  layers::LayersBackend backend = gfxPlatform::Initialized()
                                  ? gfxPlatform::GetPlatform()->GetCompositorBackend()
                                  : layers::LayersBackend::LAYERS_NONE;
  const char* backendName = GetLayersBackendName(backend);
  {
    JS::Rooted<JSString*> str(aCx, JS_NewStringCopyZ(aCx, backendName));
    JS::Rooted<JS::Value> val(aCx, StringValue(str));
    JS_SetProperty(aCx, obj, "compositor", val);
  }

  // If graphics isn't initialized yet, just stop now.
  if (!gfxPlatform::Initialized()) {
    return NS_OK;
  }

  DescribeFeatures(aCx, obj);
  return NS_OK;
}

void
GfxInfoBase::DescribeFeatures(JSContext* cx, JS::Handle<JSObject*> aOut)
{
}

bool
GfxInfoBase::InitFeatureObject(JSContext* aCx,
                               JS::Handle<JSObject*> aContainer,
                               const char* aName,
                               mozilla::gfx::FeatureStatus aFeatureStatus,
                               JS::MutableHandle<JSObject*> aOutObj)
{
  JS::Rooted<JSObject*> obj(aCx, JS_NewPlainObject(aCx));
  if (!obj) {
    return false;
  }

  const char* status = FeatureStatusToString(aFeatureStatus);

  // Set "status".
  {
    JS::Rooted<JSString*> str(aCx, JS_NewStringCopyZ(aCx, status));
    JS::Rooted<JS::Value> val(aCx, JS::StringValue(str));
    JS_SetProperty(aCx, obj, "status", val);
  }

  // Add the feature object to the container.
  {
    JS::Rooted<JS::Value> val(aCx, JS::ObjectValue(*obj));
    JS_SetProperty(aCx, aContainer, aName, val);
  }

  aOutObj.set(obj);
  return true;
}

GfxInfoCollectorBase::GfxInfoCollectorBase()
{
  GfxInfoBase::AddCollector(this);
}

GfxInfoCollectorBase::~GfxInfoCollectorBase()
{
  GfxInfoBase::RemoveCollector(this);
}