Decouple MediaSession messages from WebContents (full patch)

content/public/android/java/src/org/chromium/content_public/browser/MediaSession.java

Index: content/public/android/java/src/org/chromium/content_public/browser/MediaSession.java
diff --git a/content/public/android/java/src/org/chromium/content_public/browser/MediaSession.java b/content/public/android/java/src/org/chromium/content_public/browser/MediaSession.java
new file mode 100644
index 0000000000000000000000000000000000000000..b8efc3e7b12469420e5c94a6d0a2fe441c7af01e
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content_public/browser/MediaSession.java
@@ -0,0 +1,47 @@
+// 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_public.browser;
+
+import android.support.annotation.Nullable;
+
+import org.chromium.base.ObserverList;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.content.browser.MediaSessionImpl;
+
+/**
+ * The MediaSession Java wrapper to allow communicating with the native MediaSession object.
+ */
+public abstract class MediaSession {
+    /**
+     * @return The MediaSession associated with |contents|.
+     */
+    @Nullable
+    public static MediaSession fromWebContents(WebContents contents) {
+        // TODO(zqzhang): directly call WebContentsImpl.getMediaSession() when WebContentsImpl
+        // package restriction is removed.
+        return MediaSessionImpl.fromWebContents(contents);
+    }
+
+    /**
+     * @return The list of observers.
+     */
+    @VisibleForTesting
+    public abstract ObserverList.RewindableIterator<MediaSessionObserver> getObserversForTesting();
+
+    /**
+     * Resumes the media session.
+     */
+    public abstract void resume();
+
+    /**
+     * Suspends the media session.
+     */
+    public abstract void suspend();
+
+    /**
+     * Stops the media session.
+     */
+    public abstract void stop();
+}