Introduce content::ChildMessageFilter.

content/renderer/media/android/renderer_demuxer_android.cc

Index: content/renderer/media/android/renderer_demuxer_android.cc
diff --git a/content/renderer/media/android/renderer_demuxer_android.cc b/content/renderer/media/android/renderer_demuxer_android.cc
index 4e9749a3d10d5e877d575b79ffe8fe1be86b2132..0742b043f4d2022fbc297e0954eab327a896fb8b 100644
--- a/content/renderer/media/android/renderer_demuxer_android.cc
+++ b/content/renderer/media/android/renderer_demuxer_android.cc
@@ -6,7 +6,6 @@
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
-#include "content/child/thread_safe_sender.h"
 #include "content/common/media/media_player_messages_android.h"
 #include "content/renderer/media/android/media_source_delegate.h"
 #include "content/renderer/media/android/renderer_media_player_manager.h"
@@ -16,8 +15,7 @@
 namespace content {
 
 RendererDemuxerAndroid::RendererDemuxerAndroid()
-    : thread_safe_sender_(RenderThreadImpl::current()->thread_safe_sender()),
-      media_message_loop_(
+    : media_message_loop_(
           RenderThreadImpl::current()->GetMediaThreadMessageLoopProxy()) {}
 
 RendererDemuxerAndroid::~RendererDemuxerAndroid() {}
@@ -38,49 +36,47 @@ void RendererDemuxerAndroid::RemoveDelegate(int demuxer_client_id) {
   delegates_.Remove(demuxer_client_id);
 }
 
-bool RendererDemuxerAndroid::OnMessageReceived(const IPC::Message& message) {
+base::TaskRunner* RendererDemuxerAndroid::OverrideTaskRunnerForMessage(
+    const IPC::Message& message) {
   switch (message.type()) {
     case MediaPlayerMsg_DemuxerSeekRequest::ID:
     case MediaPlayerMsg_ReadFromDemuxer::ID:
     case MediaPlayerMsg_MediaConfigRequest::ID:
-      media_message_loop_->PostTask(FROM_HERE, base::Bind(
-          &RendererDemuxerAndroid::DispatchMessage, this, message));
-      return true;
+      return media_message_loop_;
    }
-  return false;
+  return NULL;
+}
+
+bool RendererDemuxerAndroid::HandleMessage(const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(RendererDemuxerAndroid, message)
+    IPC_MESSAGE_HANDLER(MediaPlayerMsg_DemuxerSeekRequest, OnDemuxerSeekRequest)
+    IPC_MESSAGE_HANDLER(MediaPlayerMsg_ReadFromDemuxer, OnReadFromDemuxer)
+    IPC_MESSAGE_HANDLER(MediaPlayerMsg_MediaConfigRequest, OnMediaConfigRequest)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
 }
 
 void RendererDemuxerAndroid::DemuxerReady(
     int demuxer_client_id,
     const media::DemuxerConfigs& configs) {
-  thread_safe_sender_->Send(new MediaPlayerHostMsg_DemuxerReady(
-      demuxer_client_id, configs));
+  Send(new MediaPlayerHostMsg_DemuxerReady(demuxer_client_id, configs));
 }
 
 void RendererDemuxerAndroid::ReadFromDemuxerAck(
     int demuxer_client_id,
     const media::DemuxerData& data) {
-  thread_safe_sender_->Send(new MediaPlayerHostMsg_ReadFromDemuxerAck(
-      demuxer_client_id, data));
+  Send(new MediaPlayerHostMsg_ReadFromDemuxerAck(demuxer_client_id, data));
 }
 
 void RendererDemuxerAndroid::DemuxerSeekDone(int demuxer_client_id) {
-  thread_safe_sender_->Send(new MediaPlayerHostMsg_DemuxerSeekDone(
-      demuxer_client_id));
+  Send(new MediaPlayerHostMsg_DemuxerSeekDone(demuxer_client_id));
 }
 
 void RendererDemuxerAndroid::DurationChanged(int demuxer_client_id,
                                              const base::TimeDelta& duration) {
-  thread_safe_sender_->Send(new MediaPlayerHostMsg_DurationChanged(
-      demuxer_client_id, duration));
-}
-
-void RendererDemuxerAndroid::DispatchMessage(const IPC::Message& message) {
-  IPC_BEGIN_MESSAGE_MAP(RendererDemuxerAndroid, message)
-    IPC_MESSAGE_HANDLER(MediaPlayerMsg_DemuxerSeekRequest, OnDemuxerSeekRequest)
-    IPC_MESSAGE_HANDLER(MediaPlayerMsg_ReadFromDemuxer, OnReadFromDemuxer)
-    IPC_MESSAGE_HANDLER(MediaPlayerMsg_MediaConfigRequest, OnMediaConfigRequest)
-  IPC_END_MESSAGE_MAP()
+  Send(new MediaPlayerHostMsg_DurationChanged(demuxer_client_id, duration));
 }
 
 void RendererDemuxerAndroid::OnReadFromDemuxer(