Bug 1719183 - part3 : let running audio context to keep tab awake. r=padenot,nika

Let running AudioContext also prevents tab from being suspended by asking/revoking the page awake via the browsing context.

Differential Revision: https://phabricator.services.mozilla.com/D119839

dom/ipc/ContentParent.cpp

@@ -6555,6 +6555,20 @@ mozilla::ipc::IPCResult ContentParent::RecvNotifyPositionStateChanged(
   return IPC_OK();
 }
 
+mozilla::ipc::IPCResult ContentParent::RecvAddOrRemovePageAwakeRequest(
+    const MaybeDiscarded<BrowsingContext>& aContext,
+    const bool& aShouldAddCount) {
+  if (aContext.IsNullOrDiscarded()) {
+    return IPC_OK();
+  }
+  if (aShouldAddCount) {
+    aContext.get_canonical()->AddPageAwakeRequest();
+  } else {
+    aContext.get_canonical()->RemovePageAwakeRequest();
+  }
+  return IPC_OK();
+}
+
 mozilla::ipc::IPCResult ContentParent::RecvGetModulesTrust(
     ModulePaths&& aModPaths, bool aRunAtNormalPriority,
     GetModulesTrustResolver&& aResolver) {

dom/ipc/ContentParent.h

@@ -1319,6 +1319,10 @@ class ContentParent final
       const MaybeDiscarded<BrowsingContext>& aContext,
       const PositionState& aState);
 
+  mozilla::ipc::IPCResult RecvAddOrRemovePageAwakeRequest(
+      const MaybeDiscarded<BrowsingContext>& aContext,
+      const bool& aShouldAddCount);
+
   mozilla::ipc::IPCResult RecvGetModulesTrust(
       ModulePaths&& aModPaths, bool aRunAtNormalPriority,
       GetModulesTrustResolver&& aResolver);

dom/ipc/PContent.ipdl

@@ -1657,6 +1657,14 @@ parent:
         MaybeDiscardedBrowsingContext aContext,
         PositionState aState);
 
+    /**
+     * This method will make canonical browsing context to update the count of
+     * callers which want to keep the page from being suspended even if the page
+     * is inactive.
+     */
+    async AddOrRemovePageAwakeRequest(MaybeDiscardedBrowsingContext aContext,
+                                      bool aShouldAddCount);
+
     /**
      * Due to sandboxing, a child process's UntrustedModulesProcessor cannot
      * obtain enough information about a DLL file to determine its

dom/media/mediacontrol/tests/browser/browser_suspend_inactive_tab.js

@@ -68,6 +68,26 @@ add_task(async function testInactiveTabEverStartPlayingWontBeSuspended() {
   await Promise.all([tab1.close(), tab2.close()]);
 });
 
+add_task(
+  async function testInactiveTabWithRunningAudioContextWontBeSuspended() {
+    info(`open tab and start an audio context (AC)`);
+    const tab = await createTab("about:blank");
+    await startAudioContext(tab);
+    await assertIfWindowGetSuspended(tab, { shouldBeSuspended: false });
+
+    info(`tab with running AC won't be suspended when it becomes inactive`);
+    setTabActive(tab, false);
+    await assertIfWindowGetSuspended(tab, { shouldBeSuspended: false });
+
+    info(`if AC has been suspended, then inactive tab should be suspended`);
+    await suspendAudioContext(tab);
+    await assertIfWindowGetSuspended(tab, { shouldBeSuspended: true });
+
+    info(`remove tab`);
+    await tab.close();
+  }
+);
+
 /**
  * The following are helper functions.
  */
@@ -94,3 +114,18 @@ function assertIfWindowGetSuspended(tab, { shouldBeSuspended }) {
 function setTabActive(tab, isActive) {
   tab.linkedBrowser.docShellIsActive = isActive;
 }
+
+function startAudioContext(tab) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [], async _ => {
+    content.ac = new content.AudioContext();
+    await new Promise(r => (content.ac.onstatechange = r));
+    ok(content.ac.state == "running", `Audio context started running`);
+  });
+}
+
+function suspendAudioContext(tab) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [], async _ => {
+    await content.ac.suspend();
+    ok(content.ac.state == "suspended", `Audio context is suspended`);
+  });
+}

dom/media/webaudio/AudioContext.cpp

@@ -21,8 +21,11 @@
 #include "mozilla/dom/AudioContextBinding.h"
 #include "mozilla/dom/BaseAudioContextBinding.h"
 #include "mozilla/dom/BiquadFilterNodeBinding.h"
+#include "mozilla/dom/BrowsingContext.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
 #include "mozilla/dom/ChannelMergerNodeBinding.h"
 #include "mozilla/dom/ChannelSplitterNodeBinding.h"
+#include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/ConvolverNodeBinding.h"
 #include "mozilla/dom/DelayNodeBinding.h"
 #include "mozilla/dom/DynamicsCompressorNodeBinding.h"
@@ -220,6 +223,7 @@ void AudioContext::StartBlockedAudioContextIfAllowed() {
 }
 
 void AudioContext::DisconnectFromWindow() {
+  MaybeClearPageAwakeRequest();
   nsPIDOMWindowInner* window = GetOwner();
   if (window) {
     window->RemoveAudioContext(this);
@@ -229,6 +233,7 @@ void AudioContext::DisconnectFromWindow() {
 AudioContext::~AudioContext() {
   DisconnectFromWindow();
   UnregisterWeakMemoryReporter(this);
+  MOZ_ASSERT(!mSetPageAwakeRequest, "forgot to revoke for page awake?");
 }
 
 JSObject* AudioContext::WrapObject(JSContext* aCx,
@@ -766,6 +771,7 @@ nsISerialEventTarget* AudioContext::GetMainThread() const {
 
 void AudioContext::DisconnectFromOwner() {
   mIsDisconnecting = true;
+  MaybeClearPageAwakeRequest();
   OnWindowDestroy();
   DOMEventTargetHelper::DisconnectFromOwner();
 }
@@ -894,6 +900,60 @@ void AudioContext::OnStateChanged(void* aPromise, AudioContextState aNewState) {
 
   mAudioContextState = aNewState;
   Destination()->NotifyAudioContextStateChanged();
+  MaybeUpdatePageAwakeRequest();
+}
+
+BrowsingContext* AudioContext::GetTopLevelBrowsingContext() {
+  nsCOMPtr<nsPIDOMWindowInner> window = GetParentObject();
+  if (!window) {
+    return nullptr;
+  }
+  BrowsingContext* bc = window->GetBrowsingContext();
+  if (!bc || bc->IsDiscarded()) {
+    return nullptr;
+  }
+  return bc->Top();
+}
+
+void AudioContext::MaybeUpdatePageAwakeRequest() {
+  // No need to keep page awake for offline context.
+  if (IsOffline()) {
+    return;
+  }
+
+  if (mIsShutDown) {
+    return;
+  }
+
+  if (IsRunning() && !mSetPageAwakeRequest) {
+    SetPageAwakeRequest(true);
+  } else if (!IsRunning() && mSetPageAwakeRequest) {
+    SetPageAwakeRequest(false);
+  }
+}
+
+void AudioContext::SetPageAwakeRequest(bool aShouldSet) {
+  mSetPageAwakeRequest = aShouldSet;
+  BrowsingContext* bc = GetTopLevelBrowsingContext();
+  if (!bc) {
+    return;
+  }
+  if (XRE_IsContentProcess()) {
+    ContentChild* contentChild = ContentChild::GetSingleton();
+    Unused << contentChild->SendAddOrRemovePageAwakeRequest(bc, aShouldSet);
+    return;
+  }
+  if (aShouldSet) {
+    bc->Canonical()->AddPageAwakeRequest();
+  } else {
+    bc->Canonical()->RemovePageAwakeRequest();
+  }
+}
+
+void AudioContext::MaybeClearPageAwakeRequest() {
+  if (mSetPageAwakeRequest) {
+    SetPageAwakeRequest(false);
+  }
 }
 
 nsTArray<RefPtr<mozilla::MediaTrack>> AudioContext::GetAllTracks() const {

dom/media/webaudio/AudioContext.h

@@ -51,6 +51,7 @@ class AudioDestinationNode;
 class AudioListener;
 class AudioNode;
 class BiquadFilterNode;
+class BrowsingContext;
 class ChannelMergerNode;
 class ChannelSplitterNode;
 class ConstantSourceNode;
@@ -376,6 +377,15 @@ class AudioContext final : public DOMEventTargetHelper,
   void MaybeUpdateAutoplayTelemetry();
   void MaybeUpdateAutoplayTelemetryWhenShutdown();
 
+  // If the pref `dom.suspend_inactive.enabled` is enabled, the dom window will
+  // be suspended when the window becomes inactive. In order to keep audio
+  // context running still, we will ask pages to keep awake in that situation.
+  void MaybeUpdatePageAwakeRequest();
+  void MaybeClearPageAwakeRequest();
+  void SetPageAwakeRequest(bool aShouldSet);
+
+  BrowsingContext* GetTopLevelBrowsingContext();
+
  private:
   // Each AudioContext has an id, that is passed down the MediaTracks that
   // back the AudioNodes, so we can easily compute the set of all the
@@ -434,6 +444,11 @@ class AudioContext final : public DOMEventTargetHelper,
   bool mWasEverAllowedToStart;
   bool mWasEverBlockedToStart;
   bool mWouldBeAllowedToStart;
+
+  // Whether we have set the page awake reqeust when non-offline audio context
+  // is running. That will keep the audio context being able to continue running
+  // even if the window is inactive.
+  bool mSetPageAwakeRequest = false;
 };
 
 static const dom::AudioContext::AudioContextId NO_AUDIO_CONTEXT = 0;