[PPAPI] Implement an IOStreamResource for data transmission between plugin and renderer.

ppapi/proxy/io_stream_resource.h

+// Copyright (c) 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 PPAPI_PROXY_IO_STREAM_RESOURCE_H_
+#define PPAPI_PROXY_IO_STREAM_RESOURCE_H_
+
+#include "ppapi/proxy/plugin_resource.h"
+#include "ppapi/proxy/ppapi_proxy_export.h"
+#include "ppapi/shared_impl/io_stream_shared.h"
+
+namespace ppapi {
+namespace proxy {
+
+// The IOStreamResource is used for data transmission between plugin and
+// renderer processes. It works as a ring buffer. It is implemented using
+// shared memory.
+class PPAPI_PROXY_EXPORT IOStreamResource
+    : public PluginResource,
+      public IOStreamShared {
+ protected:
+  IOStreamResource(Connection connection,
+                   PP_Instance instance,
+                   bool is_input);
+
+  IOStreamResource(Connection connection,
+                   PP_Instance instance,
+                   int pending_renderer_id,
+                   bool is_input);
+
+  virtual ~IOStreamResource();
+
+  // Initializes IOStream resource. It allocates the underlying shared circular
+  // buffer.
+  // TODO(penghuang): Support initializing asynchronously.

[bbudge, 2014/01/02 22:16:22]

We really encourage asynchronous calls for a bunch of reasons. Can we do it
asynchronously now?

[Peng, 2014/01/03 16:15:11]

Done

+  int32_t Init(uint32_t size);
+
+  // Overridden from ppapi::proxy::PluginResource
+  virtual void OnReplyReceived(const proxy::ResourceMessageReplyParams& params,
+                               const IPC::Message& msg) OVERRIDE;
+
+ private:
+  // Handle Plugin Init message.
+  void OnPluginMsgInit(const ResourceMessageReplyParams& params,
+                       uint32_t offset);
+
+  // Handle Plugin MoveLimit message.
+  void OnPluginMsgMoveLimit(const ResourceMessageReplyParams& params,
+                            uint32_t offset);
+
+  // Overridden from ppapi::IOStreamShared.
+  void MovePeerLimit(uint32_t offset) OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(IOStreamResource);
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+#endif  // PPAPI_PROXY_IO_STREAM_RESOURCE_H_