WIP: A couple of more ChannelMojo speedup ideas

ipc/mojo/ipc_message_pipe_reader.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IPC_IPC_MESSAGE_PIPE_READER_H_
 #define IPC_IPC_MESSAGE_PIPE_READER_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "ipc/ipc_message.h"
+#include "ipc/mojo/async_handle_waiter.h"
 #include "third_party/mojo/src/mojo/public/c/environment/async_waiter.h"
 #include "third_party/mojo/src/mojo/public/cpp/system/core.h"
 
 namespace IPC {
 namespace internal {
 
-class AsyncHandleWaiter;
-
 // A helper class to handle bytestream directly over mojo::MessagePipe
 // in template-method pattern. MessagePipeReader manages the lifetime
 // of given MessagePipe and participates the event loop, and
 // read the stream and call the client when it is ready.
 //
 // Each client has to:
 //
 //  * Provide a subclass implemenation of a specific use of a MessagePipe
 //    and implement callbacks.
 //  * Create the subclass instance with a MessagePipeHandle.
 //    The constructor automatically start listening on the pipe.
 //
 // MessageReader has to be used in IO thread. It isn't thread-safe.
 //
-class MessagePipeReader {
+class MessagePipeReader : public AsyncHandleWaiter::Delegate {
  public:
   class Delegate {
    public:
     virtual void OnMessageReceived(Message& message) = 0;
     virtual void OnPipeClosed(MessagePipeReader* reader) = 0;
     virtual void OnPipeError(MessagePipeReader* reader) = 0;
   };
 
   // Delay the object deletion using the current message loop.
   // This is intended to used by MessagePipeReader owners.
@@ skipping 37 matching lines @@
   bool IsValid() { return pipe_.is_valid(); }
 
   bool Send(scoped_ptr<Message> message);
   void ReadMessagesThenWait();
 
  private:
   void OnMessageReceived();
   void OnPipeClosed();
   void OnPipeError(MojoResult error);
 
+  // AsyncHandleWaiter::Delegate implementations
+  void PipeIsReady(MojoResult wait_result) override;
+  void MessageWasArrived(const void* bytes, uint32_t num_bytes) override;
+
   MojoResult ReadMessageBytes();
-  void PipeIsReady(MojoResult wait_result);
   void ReadAvailableMessages();
 
   std::vector<char>  data_buffer_;
   std::vector<MojoHandle> handle_buffer_;
   mojo::ScopedMessagePipeHandle pipe_;
   // |delegate_| and |async_waiter_| are null once the message pipe is closed.
   Delegate* delegate_;
   scoped_ptr<AsyncHandleWaiter> async_waiter_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePipeReader);
 };
 
 }  // namespace internal
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_PIPE_READER_H_