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..bfbbe64f21512df262e6f558dd0309acd615ba84 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
@@ -12,6 +12,7 @@ import android.text.TextUtils;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
+import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.metrics.MediaNotificationUma;
 import org.chromium.chrome.browser.metrics.MediaSessionUMA;
@@ -19,13 +20,16 @@ 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;
 
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.util.HashMap;
+
+import javax.annotation.Nullable;
 
 /**
  * A tab helper responsible for enabling/disabling media controls and passing
@@ -43,7 +47,7 @@ public class MediaSessionTabHelper implements MediaImageCallback {
     private Bitmap mCurrentMediaImage = null;
     private String mOrigin = null;
     private WebContents mWebContents;
-    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.
@@ -54,29 +58,41 @@ public class MediaSessionTabHelper implements MediaImageCallback {
     private MediaMetadata mCurrentMetadata = null;
     private MediaImageManager mMediaImageManager = null;
 
+    private static HashMap<Tab, MediaSessionTabHelper> sTabToHelperMap =

[whywhat, 2016/10/20 22:56:53]

having an extra method used just for testing is fine-ish, having a static map
that presumably keeps Tabs alive because it holds references to it, is a whole
different thing.

[Zhiqiang Zhang (Slow), 2016/10/21 13:43:52]

Ahh, using SparseArray<> now, with TabId as key.

+            new HashMap<Tab, MediaSessionTabHelper>();
+
+    @VisibleForTesting
+    @Nullable
+    static MediaSessionTabHelper getHelperFromTabForTesting(Tab tab) {
+        return sTabToHelperMap.get(tab);
+    }
+
+    @VisibleForTesting
+    @Nullable
+    MediaSessionDelegate getMediaSessionDelegateForTesting() {
+        return mMediaSessionDelegate;
+    }
+
     private MediaNotificationListener mControlsListener = new MediaNotificationListener() {
         @Override
         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();
         }
     };
 
@@ -92,12 +108,11 @@ 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
@@ -150,6 +165,8 @@ public class MediaSessionTabHelper implements MediaImageCallback {
                 updateNotificationMetadata();
             }
         };
+        webContents.addMediaSessionDelegate(delegate);

[whywhat, 2016/10/20 22:56:53]

nit: why "add" can WC have more than one delegate?

[Zhiqiang Zhang (Slow), 2016/10/21 13:43:52]

Currently not. Using "set" might make content::MediaSessionDelegateAndroid
complex since it must handle the "reset" case then.

+        return delegate;
     }
 
     private void setWebContents(WebContents webContents) {
@@ -157,13 +174,17 @@ public class MediaSessionTabHelper implements MediaImageCallback {
 
         cleanupWebContents();
         mWebContents = webContents;
-        if (mWebContents != null) mWebContentsObserver = createWebContentsObserver(mWebContents);
+        if (mWebContents != null) {
+            if (mMediaSessionDelegate != null) mMediaSessionDelegate.disconnectMediaSession();

[whywhat, 2016/10/20 22:56:53]

this will always be null after cleanupWebContents.

[Zhiqiang Zhang (Slow), 2016/10/21 13:43:52]

Done.

+
+            mMediaSessionDelegate = createMediaSessionDelegate(mWebContents);
+        }
         mMediaImageManager.setWebContents(mWebContents);
     }
 
     private void cleanupWebContents() {
-        if (mWebContentsObserver != null) mWebContentsObserver.destroy();
-        mWebContentsObserver = null;
+        if (mMediaSessionDelegate != null) mMediaSessionDelegate.disconnectMediaSession();
+        mMediaSessionDelegate = null;
         mWebContents = null;
     }
 
@@ -227,6 +248,7 @@ public class MediaSessionTabHelper implements MediaImageCallback {
             hideNotification();
             mTab.removeObserver(this);
             mTab = null;
+            sTabToHelperMap.remove(tab);
         }
     };
 
@@ -241,6 +263,7 @@ public class MediaSessionTabHelper implements MediaImageCallback {
         if (activity != null) {
             mPreviousVolumeControlStream = activity.getVolumeControlStream();
         }
+        sTabToHelperMap.put(tab, this);
     }
 
     /**