Added stub MediaSourcePlayer for developing behind the flag

media/base/android/media_source_player_unittest.cc

Index: media/base/android/media_source_player_unittest.cc
diff --git a/media/base/android/media_source_player_unittest.cc b/media/base/android/media_source_player_unittest.cc
index f37cf205a54b09e413551d88c7552dc5ad27d040..6aa617bd667a33974ad208d3fd47794f605b5b27 100644
--- a/media/base/android/media_source_player_unittest.cc
+++ b/media/base/android/media_source_player_unittest.cc
@@ -9,10 +9,10 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "media/base/android/audio_decoder_job.h"
+#include "media/base/android/legacy_media_source_player.h"
 #include "media/base/android/media_codec_bridge.h"
 #include "media/base/android/media_drm_bridge.h"
 #include "media/base/android/media_player_manager.h"
-#include "media/base/android/media_source_player.h"
 #include "media/base/android/media_url_interceptor.h"
 #include "media/base/android/video_decoder_job.h"
 #include "media/base/bind_to_current_loop.h"
@@ -894,7 +894,7 @@ class MediaSourcePlayerTest : public testing::Test {
   base::MessageLoop message_loop_;
   MockMediaPlayerManager manager_;
   MockDemuxerAndroid* demuxer_;  // Owned by |player_|.
-  MediaSourcePlayer player_;
+  LegacyMediaSourcePlayer player_;
 
   // Track whether a possibly async decoder callback test hook has run.
   bool decoder_callback_hook_executed_;