Deliver IPC messages together with SwapCompositorFrame

content/renderer/gpu/frame_swap_message_queue.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 CONTENT_RENDERER_GPU_FRAME_SWAP_MESSAGE_QUEUE_H_
+#define CONTENT_RENDERER_GPU_FRAME_SWAP_MESSAGE_QUEUE_H_
+
+#include <map>
+#include <vector>
+
+#include "base/auto_reset.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "base/synchronization/lock.h"
+#include "content/common/content_export.h"
+
+namespace IPC {
+class Message;
+};
+
+namespace content {
+
+// Queue used to keep track of which IPC::Messages should be sent along with a
+// particular compositor frame swap.
+class CONTENT_EXPORT FrameSwapMessageQueue
+    : public base::RefCountedThreadSafe<FrameSwapMessageQueue> {
+ public:
+  class CONTENT_EXPORT SendMessageScope {
+   public:
+    virtual ~SendMessageScope() {}
+  };
+
+  FrameSwapMessageQueue();
+
+  // Queues message to be sent on next drain.
+  //
+  // |msg| - message to queue. The method takes ownership of |msg|.
+  void QueueMessage(IPC::Message* msg);
+
+  // A SendMessageScope object must be held by the caller when this method is
+  // called.
+  //
+  // |messages| vector to store messages. it's not cleared, only appended to.
+  void DrainMessages(std::vector<IPC::Message>* messages);
+
+  // SendMessageScope is used to make sure that messages sent from different
+  // threads (impl/main) are scheduled in the right order on the IO threads.
+  //
+  // Returns an object that must be kept in scope till an IPC message containing
+  // |messages| is sent.
+  scoped_ptr<SendMessageScope> AcquireSendMessageScope();
+
+ private:
+  friend class base::RefCountedThreadSafe<FrameSwapMessageQueue>;
+
+  ~FrameSwapMessageQueue();
+
+  base::Lock lock_;
+  ScopedVector<IPC::Message> queued_messages_;
+  bool send_message_scope_aquired_;
+
+  DISALLOW_COPY_AND_ASSIGN(FrameSwapMessageQueue);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_GPU_FRAME_SWAP_MESSAGE_QUEUE_H_