Allow MediaSession in iframes to be routed

content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java

Index: content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java b/content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java
index 15350c59abee0115a5af0e1d6428b5636a3fa8a8..f5cc2d038dee66c37da7a934332814d6ff70cc0d 100644
--- a/content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java
+++ b/content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java
@@ -12,6 +12,8 @@ import org.chromium.content_public.browser.MediaSessionObserver;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.common.MediaMetadata;
 
+import java.util.HashSet;
+
 /**
  * The MediaSessionImpl Java wrapper to allow communicating with the native MediaSessionImpl object.
  * The object is owned by Java WebContentsImpl instead of native to avoid introducing a new garbage
@@ -93,16 +95,12 @@ public class MediaSessionImpl extends MediaSession {
     }
 
     @CalledByNative
-    private void mediaSessionEnabledAction(int action) {
-        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
-            mObserversIterator.next().mediaSessionEnabledAction(action);
-        }
-    }
+    private void mediaSessionActionsChanged(int[] actions) {
+        HashSet<Integer> actionSet = new HashSet<Integer>();
+        for (int action : actions) actionSet.add(action);
 

[Ted C, 2016/12/02 21:08:44]

It's unfortunate that you can't use Collections.unmodifiableSet here since it is
API 24.  You have no way of preventing the observers from modifying the set
here.  I guess if it ever becomes a problem then you just duplicate the set for
each observer.

[Zhiqiang Zhang (Slow), 2016/12/05 11:37:32]

Acknowledged.

-    @CalledByNative
-    private void mediaSessionDisabledAction(int action) {
         for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
-            mObserversIterator.next().mediaSessionDisabledAction(action);
+            mObserversIterator.next().mediaSessionActionsChanged(actionSet);
         }
     }