Link MediaSessionTabHelper with native MediaSession [CL is going to be split]

chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaSessionTabHelper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaSessionTabHelper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaSessionTabHelper.java b/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaSessionTabHelper.java
index 19252e1106b262e2fa3f854d5bc5f0e043cc2386..7cf7fb0dc209f85b8e179aa99e0808e4cc47b7c9 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaSessionTabHelper.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaSessionTabHelper.java
@@ -19,8 +19,8 @@ import org.chromium.chrome.browser.tab.EmptyTabObserver;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tab.TabObserver;
 import org.chromium.components.url_formatter.UrlFormatter;
+import org.chromium.content_public.browser.MediaSessionDelegate;
 import org.chromium.content_public.browser.WebContents;
-import org.chromium.content_public.browser.WebContentsObserver;
 import org.chromium.content_public.common.MediaMetadata;
 import org.chromium.ui.base.WindowAndroid;
 
@@ -43,7 +43,7 @@ public class MediaSessionTabHelper implements MediaImageCallback {
     private Bitmap mCurrentMediaImage = null;
     private String mOrigin = null;
     private WebContents mWebContents;

[whywhat, 2016/10/20 15:38:33]

this seems to be unused, I guess destroy() is handled by MediaSessionDelegate
now?

[Zhiqiang Zhang (Slow), 2016/10/20 16:22:32]

destroy() is now MediaSessionDelegate.mediaSessionDisconnected().

It's not fully unused now. We still need mWebContents in setWebContents().
Especially for checking `mWebContents == webContents`. Otherwise, we might end
up destroy the current delegate and create another for the same WebContents.

-    private WebContentsObserver mWebContentsObserver;
+    private MediaSessionDelegate mMediaSessionDelegate;
     private int mPreviousVolumeControlStream = AudioManager.USE_DEFAULT_STREAM_TYPE;
     private MediaNotificationInfo.Builder mNotificationInfoBuilder = null;
     // The fallback title if |mPageMetadata| is null or its title is empty.
@@ -59,24 +59,21 @@ public class MediaSessionTabHelper implements MediaImageCallback {
         public void onPlay(int actionSource) {
             MediaSessionUMA
                     .recordPlay(MediaSessionTabHelper.convertMediaActionSourceToUMA(actionSource));
-
-            mWebContents.resumeMediaSession();
+            if (mMediaSessionDelegate != null) mMediaSessionDelegate.resumeMediaSession();
         }
 
         @Override
         public void onPause(int actionSource) {
             MediaSessionUMA.recordPause(
                     MediaSessionTabHelper.convertMediaActionSourceToUMA(actionSource));
-
-            mWebContents.suspendMediaSession();
+            if (mMediaSessionDelegate != null) mMediaSessionDelegate.suspendMediaSession();
         }
 
         @Override
         public void onStop(int actionSource) {
             MediaSessionUMA
                     .recordStop(MediaSessionTabHelper.convertMediaActionSourceToUMA(actionSource));
-
-            mWebContents.stopMediaSession();
+            if (mMediaSessionDelegate != null) mMediaSessionDelegate.stopMediaSession();
         }
     };
 
@@ -92,16 +89,16 @@ public class MediaSessionTabHelper implements MediaImageCallback {
         mNotificationInfoBuilder = null;
     }
 
-    private WebContentsObserver createWebContentsObserver(WebContents webContents) {
-        return new WebContentsObserver(webContents) {
+    private MediaSessionDelegate createMediaSessionDelegate(WebContents webContents) {
+        MediaSessionDelegate delegate = new MediaSessionDelegate() {
             @Override
-            public void destroy() {
+            public void mediaSessionDisconnected() {
                 hideNotification();
-                super.destroy();
             }
 
             @Override
             public void mediaSessionStateChanged(boolean isControllable, boolean isPaused) {
+                Log.i(TAG, "Android MediaSessionStateChanged()");
                 if (!isControllable) {
                     hideNotification();
                     return;
@@ -150,6 +147,9 @@ public class MediaSessionTabHelper implements MediaImageCallback {
                 updateNotificationMetadata();
             }
         };
+        Log.i(TAG, "createMediaSessionDelegate()");
+        webContents.addMediaSessionDelegate(delegate);
+        return delegate;
     }
 
     private void setWebContents(WebContents webContents) {
@@ -157,13 +157,17 @@ public class MediaSessionTabHelper implements MediaImageCallback {
 
         cleanupWebContents();
         mWebContents = webContents;
-        if (mWebContents != null) mWebContentsObserver = createWebContentsObserver(mWebContents);
+        if (mWebContents != null) {
+            if (mMediaSessionDelegate != null) mMediaSessionDelegate.unlinkMediaSession();
+
+            mMediaSessionDelegate = createMediaSessionDelegate(mWebContents);
+        }
         mMediaImageManager.setWebContents(mWebContents);
     }
 
     private void cleanupWebContents() {
-        if (mWebContentsObserver != null) mWebContentsObserver.destroy();
-        mWebContentsObserver = null;
+        if (mMediaSessionDelegate != null) mMediaSessionDelegate.unlinkMediaSession();
+        mMediaSessionDelegate = null;
         mWebContents = null;
     }