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

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

 // Copyright 2015 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.chrome.browser.media.ui;
 
 import android.app.Activity;
 import android.content.Intent;
 import android.graphics.Bitmap;
 import android.media.AudioManager;
 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;
 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
  * media actions from the controls to the {@link org.chromium.content.browser.MediaSession}
  */
 public class MediaSessionTabHelper implements MediaImageCallback {
     private static final String TAG = "MediaSession";
 
     private static final String UNICODE_PLAY_CHARACTER = "\u25B6";
     private static final int MINIMAL_FAVICON_SIZE = 114;
 
     private Tab mTab;
     private Bitmap mPageMediaImage = null;
     private Bitmap mFavicon = null;
     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.
     private String mFallbackTitle = null;
     // The metadata set by the page.
     private MediaMetadata mPageMetadata = null;
     // The currently showing metadata.
     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();
         }
     };
 
     void hideNotification() {
         if (mTab == null) {
             return;
         }
         MediaNotificationManager.hide(mTab.getId(), R.id.media_playback_notification);
         Activity activity = getActivityFromTab(mTab);
         if (activity != null) {
             activity.setVolumeControlStream(mPreviousVolumeControlStream);
         }
         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) {
                 if (!isControllable) {
                     hideNotification();
                     return;
                 }
 
                 Intent contentIntent = Tab.createBringTabToFrontIntent(mTab.getId());
@@ skipping 32 matching lines @@
             @Override
             public void mediaSessionMetadataChanged(MediaMetadata metadata) {
                 mPageMetadata = metadata;
                 if (mPageMetadata != null) {
                     mMediaImageManager.downloadImage(mPageMetadata.getArtwork(),
                             MediaSessionTabHelper.this);
                 }
                 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) {
         if (mWebContents == webContents) return;

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

seems like we don't need mWebContents here, we could just have setWebContents()
on MediaSessionDelegate/MediaImageManager check that.

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

Maybe we can do it in a separate CL?

 
         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;
     }
 
     private final TabObserver mTabObserver = new EmptyTabObserver() {
         @Override
         public void onContentChanged(Tab tab) {
             assert tab == mTab;
             setWebContents(tab.getWebContents());
         }
 
@@ skipping 43 matching lines @@
 
         @Override
         public void onDestroyed(Tab tab) {
             assert mTab == tab;
 
             cleanupWebContents();
 
             hideNotification();
             mTab.removeObserver(this);
             mTab = null;
+            sTabToHelperMap.remove(tab);
         }
     };
 
     private MediaSessionTabHelper(Tab tab) {
         mTab = tab;
         mTab.addObserver(mTabObserver);
         mMediaImageManager = new MediaImageManager(
             MINIMAL_FAVICON_SIZE, MediaNotificationManager.getMaximumLargeIconSize());
         if (mTab.getWebContents() != null) setWebContents(tab.getWebContents());
 
         Activity activity = getActivityFromTab(mTab);
         if (activity != null) {
             mPreviousVolumeControlStream = activity.getVolumeControlStream();
         }
+        sTabToHelperMap.put(tab, this);
     }
 
     /**
      * Creates the {@link MediaSessionTabHelper} for the given {@link Tab}.
      * @param tab the tab to attach the helper to.
      */
     public static void createForTab(Tab tab) {
         new MediaSessionTabHelper(tab);
     }
 
@@ skipping 110 matching lines @@
         if (mNotificationInfoBuilder == null) return;
         mNotificationInfoBuilder.setLargeIcon(mCurrentMediaImage);
         MediaNotificationManager.show(
                 ContextUtils.getApplicationContext(), mNotificationInfoBuilder.build());
     }
 
     private Bitmap getNotificationImage() {
         return (mPageMediaImage != null) ? mPageMediaImage : mFavicon;
     }
 }