Added stub MediaSourcePlayer for developing behind the flag

content/browser/media/android/browser_demuxer_android.h

Index: content/browser/media/android/browser_demuxer_android.h
diff --git a/content/browser/media/android/browser_demuxer_android.h b/content/browser/media/android/browser_demuxer_android.h
index 407e0b3288663ab1c37541a92a266b6f9a270db5..2b746f07dcbe13f1bb92015204d2acafe1853761 100644
--- a/content/browser/media/android/browser_demuxer_android.h
+++ b/content/browser/media/android/browser_demuxer_android.h
@@ -5,6 +5,8 @@
 #ifndef CONTENT_BROWSER_MEDIA_ANDROID_BROWSER_DEMUXER_ANDROID_H_
 #define CONTENT_BROWSER_MEDIA_ANDROID_BROWSER_DEMUXER_ANDROID_H_
 
+#include <map>
+
 #include "base/id_map.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "media/base/android/demuxer_android.h"
@@ -21,8 +23,9 @@ class CONTENT_EXPORT BrowserDemuxerAndroid : public BrowserMessageFilter {
   BrowserDemuxerAndroid();
 
   // BrowserMessageFilter overrides.
-  void OverrideThreadForMessage(const IPC::Message& message,
-                                BrowserThread::ID* thread) override;
+  base::TaskRunner* OverrideTaskRunnerForMessage(
+      const IPC::Message& message) override;
+
   bool OnMessageReceived(const IPC::Message& message) override;
 
   // Returns an uninitialized demuxer implementation associated with
@@ -55,6 +58,11 @@ class CONTENT_EXPORT BrowserDemuxerAndroid : public BrowserMessageFilter {
 
   IDMap<media::DemuxerAndroidClient> demuxer_clients_;
 
+  typedef std::map<int, media::DemuxerConfigs> ConfigsPerClient;
+  ConfigsPerClient pending_configs_;
+
+  bool enable_media_thread_for_media_playback_;
+
   DISALLOW_COPY_AND_ASSIGN(BrowserDemuxerAndroid);
 };