VideoDecodeAccelerator now SupportsWeakPtr instead of being RefCountedThreadSafe.

content/common/gpu/media/omx_video_decode_accelerator.h

 // Copyright (c) 2012 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_COMMON_GPU_MEDIA_OMX_VIDEO_DECODE_ACCELERATOR_H_
 #define CONTENT_COMMON_GPU_MEDIA_OMX_VIDEO_DECODE_ACCELERATOR_H_
 
 #include <dlfcn.h>
 #include <map>
 #include <queue>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
-#include "base/memory/ref_counted.h"
 #include "base/message_loop.h"
 #include "base/shared_memory.h"
 #include "content/common/content_export.h"
 #include "media/video/video_decode_accelerator.h"
 #include "third_party/angle/include/EGL/egl.h"
 #include "third_party/angle/include/EGL/eglext.h"
 #include "third_party/openmax/il/OMX_Component.h"
 #include "third_party/openmax/il/OMX_Core.h"
 #include "third_party/openmax/il/OMX_Video.h"
 
 class Gles2TextureToEglImageTranslator;
 
 // Class to wrap OpenMAX IL accelerator behind VideoDecodeAccelerator interface.
 // The implementation assumes an OpenMAX IL 1.1.2 implementation conforming to
 // http://www.khronos.org/registry/omxil/specs/OpenMAX_IL_1_1_2_Specification.pdf
 //
-// This class lives on a single thread and DCHECKs that it is never accessed
-// from any other.  OMX callbacks are trampolined from the OMX component's
-// thread to maintain this invariant.  The only exception to thread-unsafety is
-// that references can be added from any thread (practically used only by the
-// OMX thread).
+// This class lives on a single thread (the GPU process ChildThread) and DCHECKs
+// that it is never accessed from any other.  OMX callbacks are trampolined from
+// the OMX component's thread to maintain this invariant, using |weak_this()|.
 class CONTENT_EXPORT OmxVideoDecodeAccelerator :
     public media::VideoDecodeAccelerator {
  public:
   // Does not take ownership of |client| which must outlive |*this|.
   OmxVideoDecodeAccelerator(media::VideoDecodeAccelerator::Client* client);
+  virtual ~OmxVideoDecodeAccelerator();
 
   // media::VideoDecodeAccelerator implementation.
   bool Initialize(media::VideoCodecProfile profile) OVERRIDE;
   void Decode(const media::BitstreamBuffer& bitstream_buffer) OVERRIDE;
   virtual void AssignPictureBuffers(
       const std::vector<media::PictureBuffer>& buffers) OVERRIDE;
   void ReusePictureBuffer(int32 picture_buffer_id) OVERRIDE;
   void Flush() OVERRIDE;
   void Reset() OVERRIDE;
-  void Destroy() OVERRIDE;
+  void Destroy(bool pass_ownership) OVERRIDE;
 
   void SetEglState(EGLDisplay egl_display, EGLContext egl_context);
 
+  base::WeakPtr<OmxVideoDecodeAccelerator> weak_this() { return weak_this_; }
+
  private:
-  virtual ~OmxVideoDecodeAccelerator();
-
   // Because OMX state-transitions are described solely by the "state reached"
   // (3.1.2.9.1, table 3-7 of the spec), we track what transition was requested
   // using this enum.  Note that it is an error to request a transition while
   // |*this| is in any state other than NO_TRANSITION, unless requesting
   // DESTROYING or ERRORING.
   enum CurrentStateChange {
     NO_TRANSITION,  // Not in the middle of a transition.
     INITIALIZING,
     FLUSHING,
     RESETTING,
@@ skipping 36 matching lines @@
   // (i.e. the source state is uniquely defined by the pair).
   void OnReachedIdleInInitializing();
   void OnReachedExecutingInInitializing();
   void OnReachedPauseInResetting();
   void OnReachedExecutingInResetting();
   void OnReachedIdleInDestroying();
   void OnReachedLoadedInDestroying();
   void OnReachedEOSInFlushing();
   void OnReachedInvalidInErroring();
   void ShutdownComponent();
-  void BusyLoopInDestroying();
+  void BusyLoopInDestroying(scoped_ptr<OmxVideoDecodeAccelerator> self);
 
   // Port-flushing helpers.
   void FlushIOPorts();
   void InputPortFlushDone();
   void OutputPortFlushDone();
 
   // Stop the component when any error is detected.
   void StopOnError(media::VideoDecodeAccelerator::Error error);
 
   // Determine whether we can issue fill buffer to the decoder based on the
   // current state (and outstanding state change) of the component.
   bool CanFillBuffer();
 
   // Whenever port settings change, the first thing we must do is disable the
   // port (see Figure 3-18 of the OpenMAX IL spec linked to above).  When the
   // port is disabled, the component will call us back here.  We then re-enable
   // the port once we have textures, and that's the second method below.
   void OnOutputPortDisabled();
   void OnOutputPortEnabled();
 
   // Decode bitstream buffers that were queued (see queued_bitstream_buffers_).
   void DecodeQueuedBitstreamBuffers();
 
+  // Weak pointer to |this|; used to safely trampoline calls from the OMX thread
+  // to the ChildThread.  Since |this| is kept alive until OMX is fully shut
+  // down, only the OMX->Child thread direction needs to be guarded this way.
+  base::WeakPtr<OmxVideoDecodeAccelerator> weak_this_;
+
   // True once Initialize() has returned true; before this point there's never a
   // point in calling client_->NotifyError().
   bool init_begun_;
 
   // IL-client state.
   OMX_STATETYPE client_state_;
   // See comment on CurrentStateChange above.
   CurrentStateChange current_state_change_;
 
   // Following are input port related variables.
@@ skipping 71 matching lines @@
                                     OMX_PTR event_data);
   static OMX_ERRORTYPE EmptyBufferCallback(OMX_HANDLETYPE component,
                                            OMX_PTR priv_data,
                                            OMX_BUFFERHEADERTYPE* buffer);
   static OMX_ERRORTYPE FillBufferCallback(OMX_HANDLETYPE component,
                                           OMX_PTR priv_data,
                                           OMX_BUFFERHEADERTYPE* buffer);
 };
 
 #endif  // CONTENT_COMMON_GPU_MEDIA_OMX_VIDEO_DECODE_ACCELERATOR_H_