Added stub MediaSourcePlayer for developing behind the flag

content/browser/media/android/browser_demuxer_android.cc

Index: content/browser/media/android/browser_demuxer_android.cc
diff --git a/content/browser/media/android/browser_demuxer_android.cc b/content/browser/media/android/browser_demuxer_android.cc
index ed462032fdd7f6ad3d278996d36ae4009370ecca..9669387d98da85bc74edb6f666db5350b7a5d6f8 100644
--- a/content/browser/media/android/browser_demuxer_android.cc
+++ b/content/browser/media/android/browser_demuxer_android.cc
@@ -4,7 +4,10 @@
 
 #include "content/browser/media/android/browser_demuxer_android.h"
 
+#include "base/command_line.h"
 #include "content/common/media/media_player_messages_android.h"
+#include "media/base/android/media_source_player.h"
+#include "media/base/media_switches.h"
 
 namespace content {
 
@@ -42,7 +45,7 @@ class BrowserDemuxerAndroid::Internal : public media::DemuxerAndroid {
  private:
   // Helper for DCHECKing that the ID is still registered.
   bool ClientIDExists() {
-    return demuxer_->demuxer_clients_.Lookup(demuxer_client_id_);
+    return demuxer_->Lookup(demuxer_client_id_);
   }
 
   scoped_refptr<BrowserDemuxerAndroid> demuxer_;
@@ -52,23 +55,32 @@ class BrowserDemuxerAndroid::Internal : public media::DemuxerAndroid {
 };
 
 BrowserDemuxerAndroid::BrowserDemuxerAndroid()
-    : BrowserMessageFilter(MediaPlayerMsgStart) {}
+    : BrowserMessageFilter(MediaPlayerMsgStart) {
+  enable_media_thread_for_media_playback_ =
+      base::CommandLine::ForCurrentProcess()->
+      HasSwitch(switches::kEnableMediaThreadForMediaPlayback);
+
+}
 
 BrowserDemuxerAndroid::~BrowserDemuxerAndroid() {}
 
-void BrowserDemuxerAndroid::OverrideThreadForMessage(
-    const IPC::Message& message,
-    BrowserThread::ID* thread) {
+base::TaskRunner* BrowserDemuxerAndroid::OverrideTaskRunnerForMessage(
+    const IPC::Message& message) {
+
   switch (message.type()) {
     case MediaPlayerHostMsg_DemuxerReady::ID:
     case MediaPlayerHostMsg_ReadFromDemuxerAck::ID:
     case MediaPlayerHostMsg_DurationChanged::ID:
     case MediaPlayerHostMsg_DemuxerSeekDone::ID:
-      *thread = BrowserThread::UI;
-      return;
+      return enable_media_thread_for_media_playback_ ?
+          media::GetMediaTaskRunner().get() :
+          BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI).get();
   }
+
+  return nullptr;
 }
 
+
 bool BrowserDemuxerAndroid::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(BrowserDemuxerAndroid, message)
@@ -95,20 +107,29 @@ void BrowserDemuxerAndroid::AddDemuxerClient(
     media::DemuxerAndroidClient* client) {
   DVLOG(1) << __FUNCTION__ << " peer_pid=" << peer_pid()
            << " demuxer_client_id=" << demuxer_client_id;
+
+  base::AutoLock lock(lock_);
   demuxer_clients_.AddWithID(client, demuxer_client_id);
 }
 
 void BrowserDemuxerAndroid::RemoveDemuxerClient(int demuxer_client_id) {
   DVLOG(1) << __FUNCTION__ << " peer_pid=" << peer_pid()
            << " demuxer_client_id=" << demuxer_client_id;
+
+  base::AutoLock lock(lock_);
   demuxer_clients_.Remove(demuxer_client_id);
 }
 
+media::DemuxerAndroidClient*
+BrowserDemuxerAndroid::Lookup(int demuxer_client_id) {
+  base::AutoLock lock(lock_);
+  return demuxer_clients_.Lookup(demuxer_client_id);
+}
+
 void BrowserDemuxerAndroid::OnDemuxerReady(
     int demuxer_client_id,
     const media::DemuxerConfigs& configs) {
-  media::DemuxerAndroidClient* client =
-      demuxer_clients_.Lookup(demuxer_client_id);
+  media::DemuxerAndroidClient* client = Lookup(demuxer_client_id);
   if (client)
     client->OnDemuxerConfigsAvailable(configs);
 }
@@ -116,8 +137,7 @@ void BrowserDemuxerAndroid::OnDemuxerReady(
 void BrowserDemuxerAndroid::OnReadFromDemuxerAck(
     int demuxer_client_id,
     const media::DemuxerData& data) {
-  media::DemuxerAndroidClient* client =
-      demuxer_clients_.Lookup(demuxer_client_id);
+  media::DemuxerAndroidClient* client = Lookup(demuxer_client_id);
   if (client)
     client->OnDemuxerDataAvailable(data);
 }
@@ -125,16 +145,14 @@ void BrowserDemuxerAndroid::OnReadFromDemuxerAck(
 void BrowserDemuxerAndroid::OnDemuxerSeekDone(
     int demuxer_client_id,
     const base::TimeDelta& actual_browser_seek_time) {
-  media::DemuxerAndroidClient* client =
-      demuxer_clients_.Lookup(demuxer_client_id);
+  media::DemuxerAndroidClient* client = Lookup(demuxer_client_id);
   if (client)
     client->OnDemuxerSeekDone(actual_browser_seek_time);
 }
 
 void BrowserDemuxerAndroid::OnDurationChanged(int demuxer_client_id,
                                               const base::TimeDelta& duration) {
-  media::DemuxerAndroidClient* client =
-      demuxer_clients_.Lookup(demuxer_client_id);
+  media::DemuxerAndroidClient* client = Lookup(demuxer_client_id);
   if (client)
     client->OnDemuxerDurationChanged(duration);
 }