[Android,VideoFling] Never add null players to alternative ones

chrome/browser/media/android/remote/remote_media_player_manager.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/media/android/remote/remote_media_player_manager.h"
 
 #include "chrome/browser/android/tab_android.h"
 #include "chrome/common/chrome_content_client.h"
 #include "content/common/media/media_player_messages_android.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ skipping 124 matching lines @@
 
 RemoteMediaPlayerBridge* RemoteMediaPlayerManager::CreateRemoteMediaPlayer(
     int player_id) {
   RemoteMediaPlayerBridge* player =
       new RemoteMediaPlayerBridge(player_id, GetUserAgent(), false, this);
   alternative_players_.push_back(player);
   player->Initialize();
   return player;
 }
 
-void RemoteMediaPlayerManager::SwapCurrentPlayer(int player_id) {
-  // Find the remote player
+bool RemoteMediaPlayerManager::SwapCurrentPlayer(int player_id) {
+  // Find the alternative player to swap the current one with.
   auto it = GetAlternativePlayer(player_id);
   if (it == alternative_players_.end())
-    return;
+    return false;
+
   MediaPlayerAndroid* new_player = *it;
   std::unique_ptr<MediaPlayerAndroid> old_player =
       SwapPlayer(player_id, new_player);
+  if (!old_player) {
+    // There's no player to swap with, destroy the alternative player and exit.
+    alternative_players_.erase(it);
+    return false;
+  }
+
   alternative_players_.weak_erase(it);
   alternative_players_.push_back(old_player.release());
+  return true;
 }
 
 void RemoteMediaPlayerManager::SwitchToRemotePlayer(
     int player_id,
     const std::string& casting_message) {
   DCHECK(!IsPlayingRemotely(player_id));
-  SwapCurrentPlayer(player_id);
+  if (!SwapCurrentPlayer(player_id))
+    return;
   players_playing_remotely_.insert(player_id);
   Send(new MediaPlayerMsg_DidMediaPlayerPlay(RoutingID(), player_id));
   Send(new MediaPlayerMsg_ConnectedToRemoteDevice(RoutingID(), player_id,
                                                   casting_message));
   // The remote player will want the poster bitmap, however, to avoid wasting
   // memory we don't fetch it until we are likely to need it.
   FetchPosterBitmap(player_id);
 }
 
 void RemoteMediaPlayerManager::SwitchToLocalPlayer(int player_id) {
@@ skipping 96 matching lines @@
     MediaPlayerAndroid* local_player = GetLocalPlayer(player_id);
     Send(new MediaPlayerMsg_MediaMetadataChanged(
         RoutingID(), player_id, duration, local_player->GetVideoWidth(),
         local_player->GetVideoHeight(), success));
   } else {
     BrowserMediaPlayerManager::OnMediaMetadataChanged(player_id, duration,
                                                       width, height, success);
   }
 }
 } // namespace remote_media