pjs/widget/android/nsAppShell.cpp

/* -*- Mode: c++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 4; -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 *   Mozilla Foundation
 * Portions created by the Initial Developer are Copyright (C) 2009-2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Vladimir Vukicevic <vladimir@pobox.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

// Make sure the order of included headers
#include "base/basictypes.h"
#include "nspr/prtypes.h"

#include "mozilla/Hal.h"
#include "nsAppShell.h"
#include "nsWindow.h"
#include "nsThreadUtils.h"
#include "nsICommandLineRunner.h"
#include "nsIObserverService.h"
#include "nsIAppStartup.h"
#include "nsIGeolocationProvider.h"

#include "mozilla/Services.h"
#include "mozilla/unused.h"
#include "mozilla/Preferences.h"
#include "mozilla/Hal.h"
#include "prenv.h"

#include "AndroidBridge.h"
#include <android/log.h>
#include <pthread.h>
#include <wchar.h>

#include "mozilla/dom/ScreenOrientation.h"

#ifdef MOZ_ANDROID_HISTORY
#include "nsAndroidHistory.h"
#endif

#ifdef MOZ_LOGGING
#define FORCE_PR_LOG
#include "prlog.h"
#endif

#ifdef DEBUG_ANDROID_EVENTS
#define EVLOG(args...)  ALOG(args)
#else
#define EVLOG(args...) do { } while (0)
#endif

using namespace mozilla;

#ifdef PR_LOGGING
PRLogModuleInfo *gWidgetLog = nsnull;
#endif

nsIGeolocationUpdate *gLocationCallback = nsnull;
nsAutoPtr<mozilla::AndroidGeckoEvent> gLastSizeChange;

nsAppShell *nsAppShell::gAppShell = nsnull;

NS_IMPL_ISUPPORTS_INHERITED1(nsAppShell, nsBaseAppShell, nsIObserver)

nsAppShell::nsAppShell()
    : mQueueLock("nsAppShell.mQueueLock"),
      mCondLock("nsAppShell.mCondLock"),
      mQueueCond(mCondLock, "nsAppShell.mQueueCond"),
      mNumDraws(0),
      mNumViewports(0)
{
    gAppShell = this;
}

nsAppShell::~nsAppShell()
{
    gAppShell = nsnull;
}

void
nsAppShell::NotifyNativeEvent()
{
    MutexAutoLock lock(mCondLock);
    mQueueCond.Notify();
}

#define PREFNAME_MATCH_OS  "intl.locale.matchOS"
#define PREFNAME_UA_LOCALE "general.useragent.locale"
static const char* kObservedPrefs[] = {
  PREFNAME_MATCH_OS,
  PREFNAME_UA_LOCALE,
  nsnull
};

nsresult
nsAppShell::Init()
{
#ifdef PR_LOGGING
    if (!gWidgetLog)
        gWidgetLog = PR_NewLogModule("Widget");
#endif

    mObserversHash.Init();

    nsresult rv = nsBaseAppShell::Init();
    AndroidBridge* bridge = AndroidBridge::Bridge();

    nsCOMPtr<nsIObserverService> obsServ =
        mozilla::services::GetObserverService();
    if (obsServ) {
        obsServ->AddObserver(this, "xpcom-shutdown", false);
    }

    if (!bridge)
        return rv;

    Preferences::AddStrongObservers(this, kObservedPrefs);

    bool match;
    rv = Preferences::GetBool(PREFNAME_MATCH_OS, &match);
    NS_ENSURE_SUCCESS(rv, rv);

    if (match) {
        bridge->SetSelectedLocale(EmptyString());
        return NS_OK;
    }

    nsAutoString locale;
    rv = Preferences::GetLocalizedString(PREFNAME_UA_LOCALE, &locale);
    if (NS_FAILED(rv)) {
        rv = Preferences::GetString(PREFNAME_UA_LOCALE, &locale);
    }

    bridge->SetSelectedLocale(locale);
    return rv;
}

NS_IMETHODIMP
nsAppShell::Observe(nsISupports* aSubject,
                    const char* aTopic,
                    const PRUnichar* aData)
{
    if (!strcmp(aTopic, "xpcom-shutdown")) {
        // We need to ensure no observers stick around after XPCOM shuts down
        // or we'll see crashes, as the app shell outlives XPConnect.
        mObserversHash.Clear();
        return nsBaseAppShell::Observe(aSubject, aTopic, aData);
    } else if (!strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) && aData && (
                   nsDependentString(aData).Equals(
                       NS_LITERAL_STRING(PREFNAME_UA_LOCALE)) ||
                   nsDependentString(aData).Equals(
                       NS_LITERAL_STRING(PREFNAME_MATCH_OS)))) {
        AndroidBridge* bridge = AndroidBridge::Bridge();
        if (!bridge) {
            return NS_OK;
        }

        bool match;
        nsresult rv = Preferences::GetBool(PREFNAME_MATCH_OS, &match);
        NS_ENSURE_SUCCESS(rv, rv);

        if (match) {
            bridge->SetSelectedLocale(EmptyString());
            return NS_OK;
        }

        nsAutoString locale;
        if (NS_FAILED(Preferences::GetLocalizedString(PREFNAME_UA_LOCALE,
                                                      &locale))) {
            locale = Preferences::GetString(PREFNAME_UA_LOCALE);
        }

        bridge->SetSelectedLocale(locale);
        return NS_OK;
    }
    return NS_OK;
}

void
nsAppShell::ScheduleNativeEventCallback()
{
    EVLOG("nsAppShell::ScheduleNativeEventCallback pth: %p thread: %p main: %d", (void*) pthread_self(), (void*) NS_GetCurrentThread(), NS_IsMainThread());

    // this is valid to be called from any thread, so do so.
    PostEvent(new AndroidGeckoEvent(AndroidGeckoEvent::NATIVE_POKE));
}

bool
nsAppShell::ProcessNextNativeEvent(bool mayWait)
{
    EVLOG("nsAppShell::ProcessNextNativeEvent %d", mayWait);

    nsAutoPtr<AndroidGeckoEvent> curEvent;
    AndroidGeckoEvent *nextEvent;
    {
        MutexAutoLock lock(mCondLock);

        curEvent = PopNextEvent();
        if (!curEvent && mayWait) {
            // hmm, should we really hardcode this 10s?
#if defined(DEBUG_ANDROID_EVENTS)
            PRTime t0, t1;
            EVLOG("nsAppShell: waiting on mQueueCond");
            t0 = PR_Now();

            mQueueCond.Wait(PR_MillisecondsToInterval(10000));
            t1 = PR_Now();
            EVLOG("nsAppShell: wait done, waited %d ms", (int)(t1-t0)/1000);
#else
            mQueueCond.Wait();
#endif

            curEvent = PopNextEvent();
        }
    }

    if (!curEvent)
        return false;

    // Combine subsequent events of the same type

    nextEvent = PeekNextEvent();

    while (nextEvent) {
        int curType = curEvent->Type();
        int nextType = nextEvent->Type();

        while (nextType == AndroidGeckoEvent::VIEWPORT && mNumViewports > 1) {
            // Skip this viewport change, as there's another one later and
            // processing this one will only cause more unnecessary work
            PopNextEvent();
            delete nextEvent;
            nextEvent = PeekNextEvent();
            nextType = nextEvent->Type();
        }

        while (nextType == AndroidGeckoEvent::DRAW && mLastDrawEvent &&
               mNumDraws > 1)
        {
            // skip this draw, since there's a later one already in the queue.. this will let us
            // deal with sequences that look like:
            //   MOVE DRAW MOVE DRAW MOVE DRAW
            // and end up with just
            //   MOVE DRAW
            // when we process all the events.

            // Combine the next draw event's rect with the last one in the queue
            const nsIntRect& nextRect = nextEvent->Rect();
            const nsIntRect& lastRect = mLastDrawEvent->Rect();
            int combinedArea = (lastRect.width * lastRect.height) +
                               (nextRect.width * nextRect.height);

            nsIntRect combinedRect = lastRect.Union(nextRect);
            mLastDrawEvent->Init(AndroidGeckoEvent::DRAW, combinedRect);

            // XXX We may want to consider using regions instead of rectangles.
            //     Print an error if we're upload a lot more than we would
            //     if we handled this as two separate events.
            int boundsArea = combinedRect.width * combinedRect.height;
            if (boundsArea > combinedArea * 8)
                ALOG("nsAppShell::ProcessNextNativeEvent: "
                     "Area of bounds greatly exceeds combined area: %d > %d",
                     boundsArea, combinedArea);

            // Remove the next draw event
            PopNextEvent();
            delete nextEvent;

#if defined(DEBUG_ANDROID_EVENTS)
            ALOG("# Removing DRAW event (%d outstanding)", mNumDraws);
#endif

            nextEvent = PeekNextEvent();
            nextType = nextEvent->Type();
        }

        // If the next type of event isn't the same as the current type,
        // we don't coalesce.
        if (nextType != curType)
            break;

        // Can only coalesce motion move events, for motion events
        if (curType != AndroidGeckoEvent::MOTION_EVENT)
            break;

        if (!(curEvent->Action() == AndroidMotionEvent::ACTION_MOVE &&
              nextEvent->Action() == AndroidMotionEvent::ACTION_MOVE))
            break;

#if defined(DEBUG_ANDROID_EVENTS)
        ALOG("# Removing % 2d event", curType);
#endif

        curEvent = PopNextEvent();
        nextEvent = PeekNextEvent();
    }

    EVLOG("nsAppShell: event %p %d [ndraws %d]", (void*)curEvent.get(), curEvent->Type(), mNumDraws);

    switch (curEvent->Type()) {
    case AndroidGeckoEvent::NATIVE_POKE:
        NativeEventCallback();
        break;

    case AndroidGeckoEvent::SENSOR_EVENT:
      {
        InfallibleTArray<float> values;
        mozilla::hal::SensorType type = (mozilla::hal::SensorType) curEvent->Flags();

        switch (type) {
          case hal::SENSOR_ORIENTATION:
          case hal::SENSOR_LINEAR_ACCELERATION:
          case hal::SENSOR_ACCELERATION:
          case hal::SENSOR_GYROSCOPE:
            values.AppendElement(curEvent->X());
            values.AppendElement(curEvent->Y()); 
            values.AppendElement(curEvent->Z());
            break;

        case hal::SENSOR_PROXIMITY:
            values.AppendElement(curEvent->X());
            break;

        default:
            __android_log_print(ANDROID_LOG_ERROR,
                                "Gecko", "### SENSOR_EVENT fired, but type wasn't known %d",
                                type);
        }

        const hal::SensorAccuracyType &accuracy = (hal::SensorAccuracyType) curEvent->MetaState();
        hal::SensorData sdata(type, PR_Now(), values, accuracy);
        hal::NotifySensorChange(sdata);
      }
      break;

    case AndroidGeckoEvent::LOCATION_EVENT: {
        if (!gLocationCallback)
            break;

        nsGeoPosition* p = curEvent->GeoPosition();
        if (p)
            gLocationCallback->Update(curEvent->GeoPosition());
        else
            NS_WARNING("Received location event without geoposition!");
        break;
    }

    case AndroidGeckoEvent::ACTIVITY_STOPPING: {
        if (curEvent->Flags() > 0)
            break;

        nsCOMPtr<nsIObserverService> obsServ =
            mozilla::services::GetObserverService();
        NS_NAMED_LITERAL_STRING(minimize, "heap-minimize");
        obsServ->NotifyObservers(nsnull, "memory-pressure", minimize.get());
        obsServ->NotifyObservers(nsnull, "application-background", nsnull);

        break;
    }

    case AndroidGeckoEvent::ACTIVITY_SHUTDOWN: {
        nsCOMPtr<nsIObserverService> obsServ =
            mozilla::services::GetObserverService();
        NS_NAMED_LITERAL_STRING(context, "shutdown-persist");
        obsServ->NotifyObservers(nsnull, "quit-application-granted", nsnull);
        obsServ->NotifyObservers(nsnull, "quit-application-forced", nsnull);
        obsServ->NotifyObservers(nsnull, "profile-change-net-teardown", context.get());
        obsServ->NotifyObservers(nsnull, "profile-change-teardown", context.get());
        obsServ->NotifyObservers(nsnull, "profile-before-change", context.get());
        nsCOMPtr<nsIAppStartup> appSvc = do_GetService("@mozilla.org/toolkit/app-startup;1");
        if (appSvc)
            appSvc->Quit(nsIAppStartup::eForceQuit);
        break;
    }

    case AndroidGeckoEvent::ACTIVITY_PAUSING: {
        if (curEvent->Flags() == 0) {
            // We aren't transferring to one of our own activities, so set
            // background status
            nsCOMPtr<nsIObserverService> obsServ =
                mozilla::services::GetObserverService();
            obsServ->NotifyObservers(nsnull, "application-background", nsnull);
        }

        // We really want to send a notification like profile-before-change,
        // but profile-before-change ends up shutting some things down instead
        // of flushing data
        nsIPrefService* prefs = Preferences::GetService();
        if (prefs) {
            // reset the crash loop state
            nsCOMPtr<nsIPrefBranch> prefBranch;
            prefs->GetBranch("browser.sessionstore.", getter_AddRefs(prefBranch));
            if (prefBranch)
                prefBranch->SetIntPref("recent_crashes", 0);

            prefs->SavePrefFile(nsnull);
        }

        break;
    }

    case AndroidGeckoEvent::ACTIVITY_START: {
        if (curEvent->Flags() > 0)
            break;

        nsCOMPtr<nsIObserverService> obsServ =
            mozilla::services::GetObserverService();
        obsServ->NotifyObservers(nsnull, "application-foreground", nsnull);

        break;
    }

    case AndroidGeckoEvent::SCREENSHOT: {
        if (!mBrowserApp)
            break;

        AndroidBridge* bridge = AndroidBridge::Bridge();
        if (!bridge)
            break;

        nsCOMPtr<nsIDOMWindow> domWindow;
        nsCOMPtr<nsIBrowserTab> tab;
        float scale;
        mBrowserApp->GetBrowserTab(curEvent->MetaState(), getter_AddRefs(tab));
        if (!tab)
            break;

        tab->GetWindow(getter_AddRefs(domWindow));
        if (!domWindow)
            break;

        if (NS_FAILED(tab->GetScale(&scale)))
            break;

        nsTArray<nsIntPoint> points = curEvent->Points();
        NS_ASSERTION(points.Length() == 2, "Screenshot event does not have enough coordinates");
        bridge->TakeScreenshot(domWindow, 0, 0, points[0].x, points[0].y, points[1].x, points[1].y, curEvent->MetaState(), scale);
        break;
    }

    case AndroidGeckoEvent::VIEWPORT:
    case AndroidGeckoEvent::BROADCAST: {

        if (curEvent->Characters().Length() == 0)
            break;

        nsCOMPtr<nsIObserverService> obsServ =
            mozilla::services::GetObserverService();

        const NS_ConvertUTF16toUTF8 topic(curEvent->Characters());
        const nsPromiseFlatString& data = PromiseFlatString(curEvent->CharactersExtra());

        obsServ->NotifyObservers(nsnull, topic.get(), data.get());
        break;
    }

    case AndroidGeckoEvent::LOAD_URI: {
        nsCOMPtr<nsICommandLineRunner> cmdline
            (do_CreateInstance("@mozilla.org/toolkit/command-line;1"));
        if (!cmdline)
            break;

        if (curEvent->Characters().Length() == 0)
            break;

        char *uri = ToNewUTF8String(curEvent->Characters());
        if (!uri)
            break;

        const char *argv[3] = {
            "dummyappname",
            "-remote",
            uri
        };
        nsresult rv = cmdline->Init(3, const_cast<char **>(argv), nsnull, nsICommandLine::STATE_REMOTE_AUTO);
        if (NS_SUCCEEDED(rv))
            cmdline->Run();
        nsMemory::Free(uri);
        break;
    }

    case AndroidGeckoEvent::SIZE_CHANGED: {
        // store the last resize event to dispatch it to new windows with a FORCED_RESIZE event
        if (curEvent != gLastSizeChange) {
            gLastSizeChange = new AndroidGeckoEvent(curEvent);
        }
        nsWindow::OnGlobalAndroidEvent(curEvent);
        break;
    }

    case AndroidGeckoEvent::VISITED: {
#ifdef MOZ_ANDROID_HISTORY
        nsAndroidHistory::NotifyURIVisited(nsString(curEvent->Characters()));
#endif
        break;
    }

    case AndroidGeckoEvent::NETWORK_CHANGED: {
        hal::NotifyNetworkChange(hal::NetworkInformation(curEvent->Bandwidth(),
                                                         curEvent->CanBeMetered()));
        break;
    }

    case AndroidGeckoEvent::ACTIVITY_RESUMING: {
        if (curEvent->Flags() == 0) {
            // We didn't return from one of our own activities, so restore
            // to foreground status
            nsCOMPtr<nsIObserverService> obsServ =
                mozilla::services::GetObserverService();
            obsServ->NotifyObservers(nsnull, "application-foreground", nsnull);
        }
        break;
    }

    case AndroidGeckoEvent::SCREENORIENTATION_CHANGED: {
        hal::NotifyScreenOrientationChange(static_cast<dom::ScreenOrientation>(curEvent->ScreenOrientation()));
        break;
    }

    default:
        nsWindow::OnGlobalAndroidEvent(curEvent);
    }

    EVLOG("nsAppShell: -- done event %p %d", (void*)curEvent.get(), curEvent->Type());

    return true;
}

void
nsAppShell::ResendLastResizeEvent(nsWindow* aDest) {
    if (gLastSizeChange) {
        nsWindow::OnGlobalAndroidEvent(gLastSizeChange);
    }
}

AndroidGeckoEvent*
nsAppShell::PopNextEvent()
{
    AndroidGeckoEvent *ae = nsnull;
    MutexAutoLock lock(mQueueLock);
    if (mEventQueue.Length()) {
        ae = mEventQueue[0];
        mEventQueue.RemoveElementAt(0);
        if (ae->Type() == AndroidGeckoEvent::DRAW) {
            if (--mNumDraws == 0)
                mLastDrawEvent = nsnull;
        } else if (ae->Type() == AndroidGeckoEvent::VIEWPORT) {
            mNumViewports--;
        }
    }

    return ae;
}

AndroidGeckoEvent*
nsAppShell::PeekNextEvent()
{
    AndroidGeckoEvent *ae = nsnull;
    MutexAutoLock lock(mQueueLock);
    if (mEventQueue.Length()) {
        ae = mEventQueue[0];
    }

    return ae;
}

void
nsAppShell::PostEvent(AndroidGeckoEvent *ae)
{
    {
        MutexAutoLock lock(mQueueLock);
        if (ae->Type() == AndroidGeckoEvent::SURFACE_DESTROYED) {
            // Give priority to this event, and discard any pending
            // SURFACE_CREATED events.
            mEventQueue.InsertElementAt(0, ae);
            AndroidGeckoEvent *event;
            for (int i = mEventQueue.Length()-1; i >=1; i--) {
                event = mEventQueue[i];
                if (event->Type() == AndroidGeckoEvent::SURFACE_CREATED) {
                    mEventQueue.RemoveElementAt(i);
                    delete event;
                }
            }
        } else if (ae->Type() == AndroidGeckoEvent::COMPOSITOR_PAUSE ||
                   ae->Type() == AndroidGeckoEvent::COMPOSITOR_RESUME) {
            // Give priority to these events, but maintain their order wrt each other.
            int i = 0;
            while (i < mEventQueue.Length() &&
                   (mEventQueue[i]->Type() == AndroidGeckoEvent::COMPOSITOR_PAUSE ||
                    mEventQueue[i]->Type() == AndroidGeckoEvent::COMPOSITOR_RESUME)) {
                i++;
            }
            mEventQueue.InsertElementAt(i, ae);
        } else {
            mEventQueue.AppendElement(ae);
        }

        if (ae->Type() == AndroidGeckoEvent::DRAW) {
            mNumDraws++;
            mLastDrawEvent = ae;
        } else if (ae->Type() == AndroidGeckoEvent::VIEWPORT) {
            mNumViewports++;
        }
    }
    NotifyNativeEvent();
}

void
nsAppShell::OnResume()
{
}

nsresult
nsAppShell::AddObserver(const nsAString &aObserverKey, nsIObserver *aObserver)
{
    NS_ASSERTION(aObserver != nsnull, "nsAppShell::AddObserver: aObserver is null!");
    return mObserversHash.Put(aObserverKey, aObserver) ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
}

/**
 * The XPCOM event that will call the observer on the main thread.
 */
class ObserverCaller : public nsRunnable {
public:
    ObserverCaller(nsIObserver *aObserver, const char *aTopic, const PRUnichar *aData) :
        mObserver(aObserver), mTopic(aTopic), mData(aData) {
        NS_ASSERTION(aObserver != nsnull, "ObserverCaller: aObserver is null!");
    }

    NS_IMETHOD Run() {
        ALOG("ObserverCaller::Run: observer = %p, topic = '%s')",
             (nsIObserver*)mObserver, mTopic.get());
        mObserver->Observe(nsnull, mTopic.get(), mData.get());
        return NS_OK;
    }

private:
    nsCOMPtr<nsIObserver> mObserver;
    nsCString mTopic;
    nsString mData;
};

void
nsAppShell::CallObserver(const nsAString &aObserverKey, const nsAString &aTopic, const nsAString &aData)
{
    nsCOMPtr<nsIObserver> observer;
    mObserversHash.Get(aObserverKey, getter_AddRefs(observer));

    if (!observer) {
        ALOG("nsAppShell::CallObserver: Observer was not found!");
        return;
    }

    const NS_ConvertUTF16toUTF8 sTopic(aTopic);
    const nsPromiseFlatString& sData = PromiseFlatString(aData);

    if (NS_IsMainThread()) {
        // This branch will unlikely be hit, have it just in case
        observer->Observe(nsnull, sTopic.get(), sData.get());
    } else {
        // Java is not running on main thread, so we have to use NS_DispatchToMainThread
        nsCOMPtr<nsIRunnable> observerCaller = new ObserverCaller(observer, sTopic.get(), sData.get());
        nsresult rv = NS_DispatchToMainThread(observerCaller);
        ALOG("NS_DispatchToMainThread result: %d", rv);
        unused << rv;
    }
}

void
nsAppShell::RemoveObserver(const nsAString &aObserverKey)
{
    mObserversHash.Remove(aObserverKey);
}

// NotifyObservers support.  NotifyObservers only works on main thread.

class NotifyObserversCaller : public nsRunnable {
public:
    NotifyObserversCaller(nsISupports *aSupports,
                          const char *aTopic, const PRUnichar *aData) :
        mSupports(aSupports), mTopic(aTopic), mData(aData) {
    }

    NS_IMETHOD Run() {
        nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
        if (os)
            os->NotifyObservers(mSupports, mTopic.get(), mData.get());

        return NS_OK;
    }

private:
    nsCOMPtr<nsISupports> mSupports;
    nsCString mTopic;
    nsString mData;
};

void
nsAppShell::NotifyObservers(nsISupports *aSupports,
                            const char *aTopic,
                            const PRUnichar *aData)
{
    // This isn't main thread, so post this to main thread
    nsCOMPtr<nsIRunnable> caller =
        new NotifyObserversCaller(aSupports, aTopic, aData);
    NS_DispatchToMainThread(caller);
}

// Used by IPC code
namespace mozilla {

bool ProcessNextEvent()
{
    return nsAppShell::gAppShell->ProcessNextNativeEvent(true) ? true : false;
}

void NotifyEvent()
{
    nsAppShell::gAppShell->NotifyNativeEvent();
}

}