Decouple MediaSession/MediaSessionObserver from WebContents in Java[OBSOLETE, go to the combined CL]

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
new file mode 100644
index 0000000000000000000000000000000000000000..db04ad734dbe477677bfc6e4143acada88c99541
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/MediaSessionImpl.java
@@ -0,0 +1,104 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.content.browser;
+
+import org.chromium.base.ObserverList;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.content_public.browser.MediaSession;
+import org.chromium.content_public.browser.MediaSessionObserver;
+import org.chromium.content_public.common.MediaMetadata;
+
+/**
+ * The MediaSessionImpl Java wrapper to allow communicating with the native
+ * MediaSessionImpl object.
+ */
+@JNINamespace("content")
+public class MediaSessionImpl extends MediaSession {
+    private long mNativeMediaSessionAndroid;
+
+    private ObserverList<MediaSessionObserver> mObservers;
+    private ObserverList.RewindableIterator<MediaSessionObserver> mObserversIterator;
+
+    @Override
+    public void addObserver(MediaSessionObserver observer) {
+        mObservers.addObserver(observer);
+    }
+
+    @Override
+    public void removeObserver(MediaSessionObserver observer) {
+        mObservers.removeObserver(observer);
+    }
+
+    @Override
+    public ObserverList.RewindableIterator<MediaSessionObserver> getObserversForTesting() {
+        return mObservers.rewindableIterator();
+    }
+
+    @Override
+    public void resume() {
+        nativeResume(mNativeMediaSessionAndroid);
+    }
+
+    @Override
+    public void suspend() {
+        nativeSuspend(mNativeMediaSessionAndroid);
+    }
+
+    @Override
+    public void stop() {
+        nativeStop(mNativeMediaSessionAndroid);
+    }
+
+    @CalledByNative
+    private boolean hasObservers() {
+        return !mObservers.isEmpty();
+    }
+
+    @CalledByNative
+    private void mediaSessionDestroyed() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().mediaSessionDestroyed();
+        }

[whywhat, 2016/10/28 19:14:38]

Seems like you could call tearDown from here (or even merge it with this
method).
You could also use mediaSessionDestroyed() to stop observing the MS.
Unless there's use for having these as separate methods I'd merge them.

+    }
+
+    @CalledByNative
+    private void mediaSessionStateChanged(boolean isControllable, boolean isSuspended) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().mediaSessionStateChanged(isControllable, isSuspended);
+        }
+    }
+
+    @CalledByNative
+    private void mediaSessionMetadataChanged(MediaMetadata metadata) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().mediaSessionMetadataChanged(metadata);
+        }
+    }
+
+    @CalledByNative
+    private static MediaSessionImpl create(long nativeMediaSession) {
+        return new MediaSessionImpl(nativeMediaSession);
+    }
+
+    @CalledByNative
+    private void tearDown() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().stopObserving();
+        }
+        mObservers.clear();
+        mNativeMediaSessionAndroid = 0;
+    }
+
+    private MediaSessionImpl(long nativeMediaSession) {
+        mNativeMediaSessionAndroid = nativeMediaSession;
+        mObservers = new ObserverList<MediaSessionObserver>();
+        mObserversIterator = mObservers.rewindableIterator();
+    }
+
+    private native void nativeResume(long nativeMediaSessionAndroid);
+    private native void nativeSuspend(long nativeMediaSessionAndroid);
+    private native void nativeStop(long nativeMediaSessionAndroid);
+}