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

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..0da6482bd9b1500aa9894b852a8e02c3cc459146
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content_public/browser/MediaSession.java
@@ -0,0 +1,57 @@
+// 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 org.chromium.base.ObserverList;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.JNINamespace;
+
+/**
+ * The MediaSession Java wrapper to allow communicating with the native MediaSession object.
+ */
+@JNINamespace("content")
+public abstract class MediaSession {
+    /**
+     * @return The MediaSession associated with |contents|.
+     */
+    public static MediaSession fromWebContents(WebContents contents) {
+        return nativeGetMediaSessionFromWebContents(contents);

[boliu, 2016/10/28 17:39:13]

I think this can call a static method on MediaSessionImpl, then this class
doesn't need to generate jni header or have native methods

anothe possibility, what if WebContents has a getMediaSession method? then this
can just be a pure interface

+    }
+
+    /**
+     * Add an observer to the MediaSession.
+     * @param observer The observer to add.
+     */
+    public abstract void addObserver(MediaSessionObserver observer);
+
+    /**
+     * Add an observer to the MediaSession.
+     * @param observer The observer to remove.
+     */
+    public abstract void removeObserver(MediaSessionObserver observer);
+
+    /**
+     * @return The list of observers.
+     */
+    @VisibleForTesting
+    public abstract ObserverList.RewindableIterator<MediaSessionObserver> getObserversForTesting();

[boliu, 2016/10/28 17:39:13]

where will this be used?

+
+    /**
+     * Resumes the media session.
+     */
+    public abstract void resume();
+
+    /**
+     * Suspends the media session.
+     */
+    public abstract void suspend();
+
+    /**
+     * Stops the media session.
+     */
+    public abstract void stop();
+
+    private static native MediaSession nativeGetMediaSessionFromWebContents(WebContents contents);
+}