ChannelProxy: Send() from UI thread when ChannelMojo is used.

ipc/mojo/ipc_message_pipe_reader.h

Index: ipc/mojo/ipc_message_pipe_reader.h
diff --git a/ipc/mojo/ipc_message_pipe_reader.h b/ipc/mojo/ipc_message_pipe_reader.h
index ee1d3b5caa7f046dd20117191bdc3eb7d8d19284..30d3219763e986ffa6d7bbd44aa0a57c3e249b25 100644
--- a/ipc/mojo/ipc_message_pipe_reader.h
+++ b/ipc/mojo/ipc_message_pipe_reader.h
@@ -9,6 +9,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/task_runner.h"
 #include "ipc/ipc_message.h"
 #include "mojo/public/c/environment/async_waiter.h"
 #include "mojo/public/cpp/system/core.h"
@@ -80,7 +81,10 @@ class MessagePipeReader {
   // Return true if the MessagePipe is alive.
   bool IsValid() { return pipe_.is_valid(); }
 
-  bool Send(scoped_ptr<Message> message);
+  // |Send()| doesn't notify error nor close the message pipe. The caller must
+  // handle the error if the return value isn't |MOJO_RESULT_OK|. This policy
+  // gives some flexibility when to do the error notification.
+  MojoResult Send(scoped_ptr<Message> message);
 
  private:
   static void InvokePipeIsReady(void* closure, MojoResult result);