PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_audio_input_api.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 PPAPI_THUNK_AUDIO_INPUT_API_H_
 #define PPAPI_THUNK_AUDIO_INPUT_API_H_
 
 #include <string>
 #include <vector>
 
+#include "base/memory/ref_counted.h"
 #include "ppapi/c/dev/ppb_audio_input_dev.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
 
 struct DeviceRefData;
+class TrackedCallback;
 
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_AudioInput_API {
  public:
   virtual ~PPB_AudioInput_API() {}
 
-  virtual int32_t EnumerateDevices(
-      PP_Resource* devices,
-      const PP_CompletionCallback& callback) = 0;
+  virtual int32_t EnumerateDevices(PP_Resource* devices,
+                                   scoped_refptr<TrackedCallback> callback) = 0;
   virtual int32_t Open(const std::string& device_id,
                        PP_Resource config,
                        PPB_AudioInput_Callback audio_input_callback,
                        void* user_data,
-                       const PP_CompletionCallback& callback) = 0;
+                       scoped_refptr<TrackedCallback> callback) = 0;
   virtual PP_Resource GetCurrentConfig() = 0;
   virtual PP_Bool StartCapture() = 0;
   virtual PP_Bool StopCapture() = 0;
   virtual void Close() = 0;
 
   // Trusted API.
   virtual int32_t OpenTrusted(
       const std::string& device_id,
       PP_Resource config,
-      const PP_CompletionCallback& create_callback) = 0;
+      scoped_refptr<TrackedCallback> create_callback) = 0;
   virtual int32_t GetSyncSocket(int* sync_socket) = 0;
   virtual int32_t GetSharedMemory(int* shm_handle, uint32_t* shm_size) = 0;
   virtual const std::vector<DeviceRefData>& GetDeviceRefData() const = 0;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_AUDIO_INPUT_API_H_