PPAPI: Make blocking completion callbacks work.

ppapi/shared_impl/ppb_video_capture_shared.h

Index: ppapi/shared_impl/ppb_video_capture_shared.h
diff --git a/ppapi/shared_impl/ppb_video_capture_shared.h b/ppapi/shared_impl/ppb_video_capture_shared.h
index b5c3385958e660506377616d3abef0ad78dcfe79..980a50522e0be6119a8ef2023878660b91fd6a49 100644
--- a/ppapi/shared_impl/ppb_video_capture_shared.h
+++ b/ppapi/shared_impl/ppb_video_capture_shared.h
@@ -27,13 +27,12 @@ class PPAPI_SHARED_EXPORT PPB_VideoCapture_Shared
   virtual thunk::PPB_VideoCapture_API* AsPPB_VideoCapture_API() OVERRIDE;
 
   // PPB_VideoCapture_API implementation.
-  virtual int32_t EnumerateDevices(
-      PP_Resource* devices,
-      const PP_CompletionCallback& callback) OVERRIDE;
+  virtual int32_t EnumerateDevices(PP_Resource* devices,
+                                   ApiCallbackType callback) OVERRIDE;
   virtual int32_t Open(const std::string& device_id,
                        const PP_VideoCaptureDeviceInfo_Dev& requested_info,
                        uint32_t buffer_count,
-                       const PP_CompletionCallback& callback) OVERRIDE;
+                       ApiCallbackType callback) OVERRIDE;
   virtual int32_t StartCapture() OVERRIDE;
   virtual int32_t ReuseBuffer(uint32_t buffer) OVERRIDE;
   virtual int32_t StopCapture() OVERRIDE;
@@ -56,14 +55,13 @@ class PPAPI_SHARED_EXPORT PPB_VideoCapture_Shared
 
   // Subclasses should implement these methods to do impl- and proxy-specific
   // work.
-  virtual int32_t InternalEnumerateDevices(
-      PP_Resource* devices,
-      const PP_CompletionCallback& callback) = 0;
+  virtual int32_t InternalEnumerateDevices(PP_Resource* devices,
+                                           ApiCallbackType callback) = 0;
   virtual int32_t InternalOpen(
       const std::string& device_id,
       const PP_VideoCaptureDeviceInfo_Dev& requested_info,
       uint32_t buffer_count,
-      const PP_CompletionCallback& callback) = 0;
+      ApiCallbackType callback) = 0;
   virtual int32_t InternalStartCapture() = 0;
   virtual int32_t InternalReuseBuffer(uint32_t buffer) = 0;
   virtual int32_t InternalStopCapture() = 0;