Coverity: Fix several pass-by-values.

webkit/plugins/ppapi/ppb_video_capture_impl.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 WEBKIT_PLUGINS_PPAPI_PPB_VIDEO_CAPTURE_IMPL_H_
 #define WEBKIT_PLUGINS_PPAPI_PPB_VIDEO_CAPTURE_IMPL_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 35 matching lines @@
       const media::VideoCaptureParams& device_info) OVERRIDE;
   virtual void OnInitialized(media::VideoCapture* capture,
                              bool succeeded) OVERRIDE;
 
  private:
   typedef std::vector< ::ppapi::DeviceRefData> DeviceRefDataVector;
 
   // PPB_VideoCapture_Shared implementation.
   virtual int32_t InternalEnumerateDevices(
       PP_Resource* devices,
-      PP_CompletionCallback callback) OVERRIDE;
+      const PP_CompletionCallback& callback) OVERRIDE;
   virtual int32_t InternalOpen(
       const std::string& device_id,
       const PP_VideoCaptureDeviceInfo_Dev& requested_info,
       uint32_t buffer_count,
-      PP_CompletionCallback callback) OVERRIDE;
+      const PP_CompletionCallback& callback) OVERRIDE;
   virtual int32_t InternalStartCapture() OVERRIDE;
   virtual int32_t InternalReuseBuffer(uint32_t buffer) OVERRIDE;
   virtual int32_t InternalStopCapture() OVERRIDE;
   virtual void InternalClose() OVERRIDE;
   virtual int32_t InternalStartCapture0_1(
       const PP_VideoCaptureDeviceInfo_Dev& requested_info,
       uint32_t buffer_count) OVERRIDE;
   virtual const DeviceRefDataVector& InternalGetDeviceRefData() const OVERRIDE;
 
   void ReleaseBuffers();
@@ skipping 27 matching lines @@
 
   media::VideoCapture::VideoCaptureCapability capability_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_VideoCapture_Impl);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PPB_VIDEO_CAPTURE_IMPL_H_