Bug 1495064 - part1 : refactor the logic of requesting wakelock. r=jya

HTMLMediaElement::UpdateWakeLock() is responsible for creating and releasing audio wakelock.
HTMLVideoElement::UpdateWakeLock() is responsible for creating and releasing video wakelock.

In addition, each platform would handle system wakelock properly depending on different requests.

Differential Revision: https://phabricator.services.mozilla.com/D7214

dom/html/HTMLMediaElement.cpp

@@ -4282,14 +4282,14 @@ HTMLMediaElement::UpdateWakeLock()
     Volume() > 0.0 && !mMuted && mIsAudioTrackAudible;
   // WakeLock when playing audible media.
   if (playing && isAudible) {
-    WakeLockCreate();
+    CreateAudioWakeLockIfNeeded();
   } else {
-    WakeLockRelease();
+    ReleaseAudioWakeLockIfExists();
   }
 }
 
 void
-HTMLMediaElement::WakeLockCreate()
+HTMLMediaElement::CreateAudioWakeLockIfNeeded()
 {
   if (!mWakeLock) {
     RefPtr<power::PowerManagerService> pmService =
@@ -4297,13 +4297,14 @@ HTMLMediaElement::WakeLockCreate()
     NS_ENSURE_TRUE_VOID(pmService);
 
     ErrorResult rv;
-    mWakeLock = pmService->NewWakeLock(
-      NS_LITERAL_STRING("audio-playing"), OwnerDoc()->GetInnerWindow(), rv);
+    mWakeLock = pmService->NewWakeLock(NS_LITERAL_STRING("audio-playing"),
+                                       OwnerDoc()->GetInnerWindow(),
+                                       rv);
   }
 }
 
 void
-HTMLMediaElement::WakeLockRelease()
+HTMLMediaElement::ReleaseAudioWakeLockIfExists()
 {
   if (mWakeLock) {
     ErrorResult rv;
@@ -4313,6 +4314,12 @@ HTMLMediaElement::WakeLockRelease()
   }
 }
 
+void
+HTMLMediaElement::WakeLockRelease()
+{
+  ReleaseAudioWakeLockIfExists();
+}
+
 HTMLMediaElement::OutputMediaStream::OutputMediaStream()
   : mNextAvailableTrackID(1)
   , mFinishWhenEnded(false)

dom/html/HTMLMediaElement.h

@@ -844,8 +844,6 @@ protected:
 
   void SetDecoder(MediaDecoder* aDecoder);
 
-  void UpdateWakeLock();
-
   // Holds references to the DOM wrappers for the MediaStreams that we're
   // writing to.
   struct OutputMediaStream {
@@ -882,11 +880,14 @@ protected:
   void ChangeNetworkState(nsMediaNetworkState aState);
 
   /**
-   * These two methods are called when mPaused is changed to ensure we have
-   * a wake lock active when we're playing audibly.
+   * The MediaElement will be responsible for creating and releasing the audio
+   * wakelock depending on the playing and audible state.
    */
-  virtual void WakeLockCreate();
   virtual void WakeLockRelease();
+  virtual void UpdateWakeLock();
+
+  void CreateAudioWakeLockIfNeeded();
+  void ReleaseAudioWakeLockIfExists();
   RefPtr<WakeLock> mWakeLock;
 
   /**

dom/html/HTMLVideoElement.cpp

@@ -296,32 +296,29 @@ HTMLVideoElement::GetVideoPlaybackQuality()
   return playbackQuality.forget();
 }
 
-void
-HTMLVideoElement::WakeLockCreate()
-{
-  HTMLMediaElement::WakeLockCreate();
-  UpdateScreenWakeLock();
-}
 
 void
 HTMLVideoElement::WakeLockRelease()
 {
-  UpdateScreenWakeLock();
   HTMLMediaElement::WakeLockRelease();
+  ReleaseVideoWakeLockIfExists();
 }
 
 void
-HTMLVideoElement::UpdateScreenWakeLock()
+HTMLVideoElement::UpdateWakeLock()
 {
-  if (mScreenWakeLock && mPaused) {
-    ErrorResult rv;
-    mScreenWakeLock->Unlock(rv);
-    rv.SuppressException();
-    mScreenWakeLock = nullptr;
-    return;
+  HTMLMediaElement::UpdateWakeLock();
+  if (!mPaused) {
+    CreateVideoWakeLockIfNeeded();
+  } else {
+    ReleaseVideoWakeLockIfExists();
+  }
 }
 
-  if (!mScreenWakeLock && !mPaused && HasVideo()) {
+void
+HTMLVideoElement::CreateVideoWakeLockIfNeeded()
+{
+  if (!mScreenWakeLock && HasVideo()) {
     RefPtr<power::PowerManagerService> pmService =
       power::PowerManagerService::GetInstance();
     NS_ENSURE_TRUE_VOID(pmService);
@@ -333,6 +330,18 @@ HTMLVideoElement::UpdateScreenWakeLock()
   }
 }
 
+void
+HTMLVideoElement::ReleaseVideoWakeLockIfExists()
+{
+  if (mScreenWakeLock) {
+    ErrorResult rv;
+    mScreenWakeLock->Unlock(rv);
+    rv.SuppressException();
+    mScreenWakeLock = nullptr;
+    return;
+  }
+}
+
 void
 HTMLVideoElement::Init()
 {

dom/html/HTMLVideoElement.h

@@ -155,9 +155,17 @@ protected:
 
   virtual JSObject* WrapNode(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
-  virtual void WakeLockCreate() override;
-  virtual void WakeLockRelease() override;
-  void UpdateScreenWakeLock();
+  /**
+   * We create video wakelock when the video is playing and release it when
+   * video pauses. Note, the actual platform wakelock will automatically be
+   * released when the page is in the background, so we don't need to check the
+   * video's visibility by ourselves.
+   */
+  void WakeLockRelease() override;
+  void UpdateWakeLock() override;
+
+  void CreateVideoWakeLockIfNeeded();
+  void ReleaseVideoWakeLockIfExists();
 
   RefPtr<WakeLock> mScreenWakeLock;