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..242c7dc5983d05e2ee94df74099b21745cb766c2 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_codec_player.h"

[xhwang, 2015/05/06 17:42:44]

hmm, wondering why we need this...

[Tima Vaisburd, 2015/05/08 07:30:53]

media::GetMediaTaskRunner() is defined there

[xhwang, 2015/05/08 17:12:36]

It's a bit odd since BDA can also be used by MediaSourcePlayer. It's not a big
issue though.

+#include "media/base/media_switches.h"
 
 namespace content {
 
@@ -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);

[xhwang, 2015/05/06 17:42:44]

Actually, how about this. 

Instead of having a enable_media_thread_for_media_playback_ member, just have a
task_runner_ member, which will be initialized in the ctor. Then in
OverrideTaskRunnerForMessage(), you can just return the task_runner_.

With that, you can DCHECK we are on the correct thread in each member functions,
which will make the threading model more clear.

[Tima Vaisburd, 2015/05/08 07:30:53]

Done.

+
+}
 
 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;

[xhwang, 2015/05/06 17:42:44]

When nullptr is returned, a message will be dispatched on the IO thread, which
is unexpected.

Add NOTREACHED() before return?

[Tima Vaisburd, 2015/05/08 07:30:53]

Actually, I saw some messages there. I did not identify them by name, but I
believe they were other media player messages that were later dispatched on UI
thread. Can it be that the message filters form a chain?

[xhwang, 2015/05/08 17:12:36]

Acknowledged.

You are right. I believe the dispatcher tries each MessageFilter to see whether
the message can be handled by this MF.

 }
 
+

[xhwang, 2015/05/06 17:42:44]

nit: remove extra line.

[Tima Vaisburd, 2015/05/08 07:30:53]

Done.

 bool BrowserDemuxerAndroid::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(BrowserDemuxerAndroid, message)
@@ -95,12 +107,19 @@ void BrowserDemuxerAndroid::AddDemuxerClient(
     media::DemuxerAndroidClient* client) {
   DVLOG(1) << __FUNCTION__ << " peer_pid=" << peer_pid()
            << " demuxer_client_id=" << demuxer_client_id;
+
   demuxer_clients_.AddWithID(client, demuxer_client_id);
+
+  if (pending_configs_.count(demuxer_client_id)) {
+    client->OnDemuxerConfigsAvailable(pending_configs_[demuxer_client_id]);
+    pending_configs_.erase(demuxer_client_id);
+  }
 }
 
 void BrowserDemuxerAndroid::RemoveDemuxerClient(int demuxer_client_id) {
   DVLOG(1) << __FUNCTION__ << " peer_pid=" << peer_pid()
            << " demuxer_client_id=" << demuxer_client_id;
+
   demuxer_clients_.Remove(demuxer_client_id);
 }
 
@@ -109,8 +128,11 @@ void BrowserDemuxerAndroid::OnDemuxerReady(
     const media::DemuxerConfigs& configs) {
   media::DemuxerAndroidClient* client =
       demuxer_clients_.Lookup(demuxer_client_id);
+
   if (client)
     client->OnDemuxerConfigsAvailable(configs);
+  else
+    pending_configs_[demuxer_client_id] = configs;
 }
 
 void BrowserDemuxerAndroid::OnReadFromDemuxerAck(
@@ -118,6 +140,7 @@ void BrowserDemuxerAndroid::OnReadFromDemuxerAck(
     const media::DemuxerData& data) {
   media::DemuxerAndroidClient* client =
       demuxer_clients_.Lookup(demuxer_client_id);
+
   if (client)
     client->OnDemuxerDataAvailable(data);
 }
@@ -127,6 +150,7 @@ void BrowserDemuxerAndroid::OnDemuxerSeekDone(
     const base::TimeDelta& actual_browser_seek_time) {
   media::DemuxerAndroidClient* client =
       demuxer_clients_.Lookup(demuxer_client_id);
+
   if (client)
     client->OnDemuxerSeekDone(actual_browser_seek_time);
 }
@@ -135,8 +159,11 @@ void BrowserDemuxerAndroid::OnDurationChanged(int demuxer_client_id,
                                               const base::TimeDelta& duration) {
   media::DemuxerAndroidClient* client =
       demuxer_clients_.Lookup(demuxer_client_id);
+
   if (client)
     client->OnDemuxerDurationChanged(duration);
+  else
+    pending_configs_[demuxer_client_id].duration = duration;
 }
 
 }  // namespace content