Reuse media sources in demo apps.

Especially the cast demo app benefits from this feature as it can keep its
ConcatenatingMediaSource all the time without having to repopulate it
when switching players.

Issue:#3498

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=187866048

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/PlayerManager.java

@@ -79,8 +79,8 @@ import java.util.ArrayList;
   private final CastPlayer castPlayer;
   private final ArrayList<DemoUtil.Sample> mediaQueue;
   private final QueuePositionListener queuePositionListener;
+  private final ConcatenatingMediaSource concatenatingMediaSource;
 
-  private ConcatenatingMediaSource concatenatingMediaSource;
   private boolean castMediaQueueCreationPending;
   private int currentItemIndex;
   private Player currentPlayer;
@@ -116,6 +116,7 @@ import java.util.ArrayList;
     this.castControlView = castControlView;
     mediaQueue = new ArrayList<>();
     currentItemIndex = C.INDEX_UNSET;
+    concatenatingMediaSource = new ConcatenatingMediaSource();
 
     DefaultTrackSelector trackSelector = new DefaultTrackSelector(BANDWIDTH_METER);
     RenderersFactory renderersFactory = new DefaultRenderersFactory(context, null);
@@ -154,9 +155,8 @@ import java.util.ArrayList;
    */
   public void addItem(Sample sample) {
     mediaQueue.add(sample);
-    if (currentPlayer == exoPlayer) {
     concatenatingMediaSource.addMediaSource(buildMediaSource(sample));
-    } else {
+    if (currentPlayer == castPlayer) {
       castPlayer.addItems(buildMediaQueueItem(sample));
     }
   }
@@ -185,9 +185,8 @@ import java.util.ArrayList;
    * @return Whether the removal was successful.
    */
   public boolean removeItem(int itemIndex) {
-    if (currentPlayer == exoPlayer) {
     concatenatingMediaSource.removeMediaSource(itemIndex);
-    } else {
+    if (currentPlayer == castPlayer) {
       if (castPlayer.getPlaybackState() != Player.STATE_IDLE) {
         Timeline castTimeline = castPlayer.getCurrentTimeline();
         if (castTimeline.getPeriodCount() <= itemIndex) {
@@ -214,9 +213,8 @@ import java.util.ArrayList;
    */
   public boolean moveItem(int fromIndex, int toIndex) {
     // Player update.
-    if (currentPlayer == exoPlayer) {
     concatenatingMediaSource.moveMediaSource(fromIndex, toIndex);
-    } else if (castPlayer.getPlaybackState() != Player.STATE_IDLE) {
+    if (currentPlayer == castPlayer && castPlayer.getPlaybackState() != Player.STATE_IDLE) {
       Timeline castTimeline = castPlayer.getCurrentTimeline();
       int periodCount = castTimeline.getPeriodCount();
       if (periodCount <= fromIndex || periodCount <= toIndex) {
@@ -262,6 +260,7 @@ import java.util.ArrayList;
   public void release() {
     currentItemIndex = C.INDEX_UNSET;
     mediaQueue.clear();
+    concatenatingMediaSource.clear();
     castPlayer.setSessionAvailabilityListener(null);
     castPlayer.release();
     localPlayerView.setPlayer(null);
@@ -349,10 +348,6 @@ import java.util.ArrayList;
     // Media queue management.
     castMediaQueueCreationPending = currentPlayer == castPlayer;
     if (currentPlayer == exoPlayer) {
-      concatenatingMediaSource = new ConcatenatingMediaSource();
-      for (int i = 0; i < mediaQueue.size(); i++) {
-        concatenatingMediaSource.addMediaSource(buildMediaSource(mediaQueue.get(i)));
-      }
       exoPlayer.prepare(concatenatingMediaSource);
     }
 

demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -118,6 +118,7 @@ public class PlayerActivity extends Activity
 
   private DataSource.Factory mediaDataSourceFactory;
   private SimpleExoPlayer player;
+  private MediaSource mediaSource;
   private DefaultTrackSelector trackSelector;
   private TrackSelectionHelper trackSelectionHelper;
   private DebugTextViewHelper debugViewHelper;
@@ -253,9 +254,8 @@ public class PlayerActivity extends Activity
   // Internal methods
 
   private void initializePlayer() {
+    if (player == null) {
       Intent intent = getIntent();
-    boolean needNewPlayer = player == null;
-    if (needNewPlayer) {
       TrackSelection.Factory adaptiveTrackSelectionFactory =
           new AdaptiveTrackSelection.Factory(BANDWIDTH_METER);
       trackSelector = new DefaultTrackSelector(adaptiveTrackSelectionFactory);
@@ -315,13 +315,13 @@ public class PlayerActivity extends Activity
       playerView.setPlaybackPreparer(this);
       debugViewHelper = new DebugTextViewHelper(player, debugTextView);
       debugViewHelper.start();
-    }
+
       String action = intent.getAction();
       Uri[] uris;
       String[] extensions;
       if (ACTION_VIEW.equals(action)) {
-      uris = new Uri[]{intent.getData()};
-      extensions = new String[]{intent.getStringExtra(EXTENSION_EXTRA)};
+        uris = new Uri[] {intent.getData()};
+        extensions = new String[] {intent.getStringExtra(EXTENSION_EXTRA)};
       } else if (ACTION_VIEW_LIST.equals(action)) {
         String[] uriStrings = intent.getStringArrayExtra(URI_LIST_EXTRA);
         uris = new Uri[uriStrings.length];
@@ -344,8 +344,8 @@ public class PlayerActivity extends Activity
       for (int i = 0; i < uris.length; i++) {
         mediaSources[i] = buildMediaSource(uris[i], extensions[i], mainHandler, eventLogger);
       }
-    MediaSource mediaSource = mediaSources.length == 1 ? mediaSources[0]
-        : new ConcatenatingMediaSource(mediaSources);
+      mediaSource =
+          mediaSources.length == 1 ? mediaSources[0] : new ConcatenatingMediaSource(mediaSources);
       String adTagUriString = intent.getStringExtra(AD_TAG_URI_EXTRA);
       if (adTagUriString != null) {
         Uri adTagUri = Uri.parse(adTagUriString);
@@ -362,6 +362,7 @@ public class PlayerActivity extends Activity
       } else {
         releaseAdsLoader();
       }
+    }
     boolean haveResumePosition = resumeWindow != C.INDEX_UNSET;
     if (haveResumePosition) {
       player.seekTo(resumeWindow, resumePosition);
@@ -424,6 +425,7 @@ public class PlayerActivity extends Activity
       updateResumePosition();
       player.release();
       player = null;
+      mediaSource = null;
       trackSelector = null;
       trackSelectionHelper = null;
       eventLogger = null;