VideoDecodeAccelerator now SupportsWeakPtr instead of being RefCountedThreadSafe.

media/video/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 MEDIA_VIDEO_VIDEO_DECODE_ACCELERATOR_H_
 #define MEDIA_VIDEO_VIDEO_DECODE_ACCELERATOR_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/weak_ptr.h"
 #include "media/base/bitstream_buffer.h"
 #include "media/base/video_decoder_config.h"
 #include "media/video/picture.h"
 #include "ui/gfx/size.h"
 
 namespace media {
 
 // Video decoder interface.
 // This interface is extended by the various components that ultimately
 // implement the backend of PPB_VideoDecode_Dev.
-//
-// No thread-safety guarantees are implied by the use of RefCountedThreadSafe
-// below.
 class MEDIA_EXPORT VideoDecodeAccelerator
-    : public base::RefCountedThreadSafe<VideoDecodeAccelerator> {
+    : public base::SupportsWeakPtr<VideoDecodeAccelerator> {
  public:
+  virtual ~VideoDecodeAccelerator();
+
   // Enumeration of potential errors generated by the API.
   // Note: Keep these in sync with PP_VideoDecodeError_Dev.
   enum Error {
     // An operation was attempted during an incompatible decoder state.
     ILLEGAL_STATE = 1,
     // Invalid argument was passed to an API method.
     INVALID_ARGUMENT,
     // Encoded input is unreadable.
     UNREADABLE_INPUT,
     // A failure occurred at the browser layer or one of its dependencies.
@@ skipping 83 matching lines @@
   // Resets the decoder: all pending inputs are dropped immediately and the
   // decoder returned to a state ready for further Decode()s, followed by
   // NotifyResetDone() being called on the client.  Can be used to implement
   // "seek".
   virtual void Reset() = 0;
 
   // Destroys the decoder: all pending inputs are dropped immediately and the
   // component is freed.  This call may asynchornously free system resources,
   // but its client-visible effects are synchronous.  After this method returns
   // no more callbacks will be made on the client.
-  virtual void Destroy() = 0;
-
- protected:
-  friend class base::RefCountedThreadSafe<VideoDecodeAccelerator>;
-  virtual ~VideoDecodeAccelerator();
+  // Because the client interface is synchronous but implementations may be
+  // asynchronous, the caller (who may own |this|) can pass ownership of the VDA
+  // *to* the VDA for hidden shenaniganary.  |self| may be NULL if ownership
+  // doesn't need to transfer.
+  virtual void Destroy(scoped_ptr<VideoDecodeAccelerator> self) = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_VIDEO_DECODE_ACCELERATOR_H_