Add PepperViewProxy to protect PepperView and ChromotingInstance on shutdown

remoting/client/plugin/pepper_view_proxy.h

+// Copyright (c) 2011 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.
+
+// PepperViewProxy is used to invoke PepperView object on pepper thread. It
+// has the same interface as PepperView. When a method calls is received on
+// any chromoting threads it delegates the method call to pepper thread.
+// It also provide a detach mechanism so that when PepperView object is
+// destroyed PepperViewProxy will not call it anymore. This is important in
+// providing a safe shutdown of ChromotingInstance and PepperView.
+
+// This object is accessed on chromoting threads and pepper thread. The internal
+// PepperView object is only accessed on pepper thread so as the Detach() method
+// call.
+
+#ifndef REMOTING_CLIENT_PLUGIN_PEPPER_VIEW_PROXY_H_
+#define REMOTING_CLIENT_PLUGIN_PEPPER_VIEW_PROXY_H_
+
+#include "base/ref_counted.h"
+#include "remoting/client/plugin/pepper_view.h"
+
+namespace remoting {
+
+class ChromotingInstance;
+class ClientContext;
+
+class PepperViewProxy : public base::RefCountedThreadSafe<PepperViewProxy>,
+                        public ChromotingView,
+                        public FrameConsumer {
+ public:
+  PepperViewProxy(ChromotingInstance* instance, PepperView* view);
+  virtual ~PepperViewProxy();
+
+  // ChromotingView implementation.
+  virtual bool Initialize();
+  virtual void TearDown();
+  virtual void Paint();
+  virtual void SetSolidFill(uint32 color);
+  virtual void UnsetSolidFill();
+  virtual void SetConnectionState(ConnectionState state);
+  virtual void SetViewport(int x, int y, int width, int height);
+
+  // FrameConsumer implementation.
+  virtual void AllocateFrame(media::VideoFrame::Format format,
+                             size_t width,
+                             size_t height,
+                             base::TimeDelta timestamp,
+                             base::TimeDelta duration,
+                             scoped_refptr<media::VideoFrame>* frame_out,
+                             Task* done);
+  virtual void ReleaseFrame(media::VideoFrame* frame);
+  virtual void OnPartialFrameOutput(media::VideoFrame* frame,
+                                    UpdatedRects* rects,
+                                    Task* done);
+
+  // Remove the reference to |instance_| and |view_| by setting the value to
+  // NULL.
+  // This method should only be called on pepper thread.
+  void Detach();
+
+ private:
+  // This variable is accessed on chromoting threads and pepper thread.
+  // This is initialized when this object is constructed. Its value is reset
+  // to NULL on pepper thread when Detach() is called and there will be no
+  // other threads accessing this variable at the same time. Given the above
+  // conditions locking this variable is not necessary.
+  ChromotingInstance* instance_;
+
+  // This variable is only accessed on the pepper thread. Locking is not
+  // necessary.
+  PepperView* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(PepperViewProxy);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_CLIENT_PLUGIN_PEPPER_VIEW_PROXY_H_