Bug 1208316 - Implement MediaStream.active. r=jib, r=smaug

MozReview-Commit-ID: Fzk5vepqQ35

--HG--
extra : rebase_source : 1ddf804e4ca8604b36cf0e8b4752f638c45c9561

dom/media/DOMMediaStream.cpp

@@ -366,7 +366,8 @@ DOMMediaStream::DOMMediaStream(nsPIDOMWindowInner* aWindow,
   : mLogicalStreamStartTime(0), mWindow(aWindow),
     mInputStream(nullptr), mOwnedStream(nullptr), mPlaybackStream(nullptr),
     mTracksPendingRemoval(0), mTrackSourceGetter(aTrackSourceGetter),
-    mTracksCreated(false), mNotifiedOfMediaStreamGraphShutdown(false)
+    mTracksCreated(false), mNotifiedOfMediaStreamGraphShutdown(false),
+    mActive(false)
 {
   nsresult rv;
   nsCOMPtr<nsIUUIDGenerator> uuidgen =
@@ -618,13 +619,13 @@ DOMMediaStream::RemoveTrack(MediaStreamTrack& aTrack)
   // cases blocking the underlying track should be avoided.
   if (!aTrack.Ended()) {
     BlockPlaybackTrack(toRemove);
+
+    bool removed = mTracks.RemoveElement(toRemove);
+    if (removed) {
+      NotifyTrackRemoved(&aTrack);
+    }
   }
 
-  DebugOnly<bool> removed = mTracks.RemoveElement(toRemove);
-  MOZ_ASSERT(removed);
-
-  NotifyTrackRemoved(&aTrack);
-
   LOG(LogLevel::Debug, ("DOMMediaStream %p Removed track %p", this, &aTrack));
 }
 
@@ -730,6 +731,12 @@ DOMMediaStream::CloneInternal(TrackForwardingOption aForwarding)
   return newStream.forget();
 }
 
+bool
+DOMMediaStream::Active() const
+{
+  return mActive;
+}
+
 MediaStreamTrack*
 DOMMediaStream::GetTrackById(const nsAString& aId) const
 {
@@ -1179,6 +1186,28 @@ DOMMediaStream::NotifyTracksCreated()
   CheckTracksAvailable();
 }
 
+void
+DOMMediaStream::NotifyActive()
+{
+  LOG(LogLevel::Info, ("DOMMediaStream %p NotifyActive(). ", this));
+
+  MOZ_ASSERT(mActive);
+  for (int32_t i = mTrackListeners.Length() - 1; i >= 0; --i) {
+    mTrackListeners[i]->NotifyActive();
+  }
+}
+
+void
+DOMMediaStream::NotifyInactive()
+{
+  LOG(LogLevel::Info, ("DOMMediaStream %p NotifyInactive(). ", this));
+
+  MOZ_ASSERT(!mActive);
+  for (int32_t i = mTrackListeners.Length() - 1; i >= 0; --i) {
+    mTrackListeners[i]->NotifyInactive();
+  }
+}
+
 void
 DOMMediaStream::CheckTracksAvailable()
 {
@@ -1243,6 +1272,24 @@ DOMMediaStream::NotifyTrackAdded(const RefPtr<MediaStreamTrack>& aTrack)
   for (int32_t i = mTrackListeners.Length() - 1; i >= 0; --i) {
     mTrackListeners[i]->NotifyTrackAdded(aTrack);
   }
+
+  if (mActive) {
+    return;
+  }
+
+  // Check if we became active.
+  bool active = false;
+  for (auto port : mTracks) {
+    if (!port->GetTrack()->Ended()) {
+      active = true;
+      break;
+    }
+  }
+
+  if (active) {
+    mActive = true;
+    NotifyActive();
+  }
 }
 
 void
@@ -1254,11 +1301,31 @@ DOMMediaStream::NotifyTrackRemoved(const RefPtr<MediaStreamTrack>& aTrack)
 
   for (int32_t i = mTrackListeners.Length() - 1; i >= 0; --i) {
     mTrackListeners[i]->NotifyTrackRemoved(aTrack);
+
   }
 
   // Don't call RecomputePrincipal here as the track may still exist in the
   // playback stream in the MediaStreamGraph. It will instead be called when the
   // track has been confirmed removed by the graph. See BlockPlaybackTrack().
+
+  if (!mActive) {
+    NS_ASSERTION(false, "Shouldn't remove a live track if already inactive");
+    return;
+  }
+
+  // Check if we became inactive.
+  bool active = false;
+  for (auto port : mTracks) {
+    if (!port->GetTrack()->Ended()) {
+      active = true;
+      break;
+    }
+  }
+
+  if (!active) {
+    mActive = false;
+    NotifyInactive();
+  }
 }
 
 nsresult

dom/media/DOMMediaStream.h

@@ -226,18 +226,30 @@ public:
     virtual ~TrackListener() {}
 
     /**
-     * Called when the DOMMediaStream has a new track added, either by
-     * JS (addTrack()) or the source creating one.
+     * Called when the DOMMediaStream has a live track added, either by
+     * script (addTrack()) or the source creating one.
      */
     virtual void
     NotifyTrackAdded(const RefPtr<MediaStreamTrack>& aTrack) {};
 
     /**
-     * Called when the DOMMediaStream removes a track, either by
-     * JS (removeTrack()) or the source ending it.
+     * Called when the DOMMediaStream removes a live track from playback, either
+     * by script (removeTrack(), track.stop()) or the source ending it.
      */
     virtual void
     NotifyTrackRemoved(const RefPtr<MediaStreamTrack>& aTrack) {};
+
+    /**
+     * Called when the DOMMediaStream has become active.
+     */
+    virtual void
+    NotifyActive() {};
+
+    /**
+     * Called when the DOMMediaStream has become inactive.
+     */
+    virtual void
+    NotifyInactive() {};
   };
 
   /**
@@ -363,6 +375,8 @@ public:
   /** Identical to CloneInternal(TrackForwardingOption::EXPLICIT) */
   already_AddRefed<DOMMediaStream> Clone();
 
+  bool Active() const;
+
   IMPL_EVENT_HANDLER(addtrack)
 
   // NON-WebIDL
@@ -599,6 +613,12 @@ protected:
   // created.
   void NotifyTracksCreated();
 
+  // Dispatches NotifyActive() to all registered track listeners.
+  void NotifyActive();
+
+  // Dispatches NotifyInactive() to all registered track listeners.
+  void NotifyInactive();
+
   // Dispatches NotifyTrackAdded() to all registered track listeners.
   void NotifyTrackAdded(const RefPtr<MediaStreamTrack>& aTrack);
 
@@ -699,6 +719,9 @@ protected:
   // The track listeners subscribe to changes in this stream's track set.
   nsTArray<TrackListener*> mTrackListeners;
 
+  // True if this stream has live tracks.
+  bool mActive;
+
 private:
   void NotifyPrincipalChanged();
   // Principal identifying who may access the collected contents of this stream.

dom/webidl/MediaStream.webidl

@@ -36,9 +36,7 @@ interface MediaStream : EventTarget {
     void                       addTrack (MediaStreamTrack track);
     void                       removeTrack (MediaStreamTrack track);
     MediaStream                clone ();
-    // readonly    attribute boolean      active;
-    //             attribute EventHandler onactive;
-    //             attribute EventHandler oninactive;
+    readonly    attribute boolean      active;
                 attribute EventHandler onaddtrack;
     //             attribute EventHandler onremovetrack;
     readonly attribute double currentTime;