Coverity: Fix several pass-by-values.

webkit/plugins/ppapi/ppb_video_capture_impl.cc

 // 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.
 
 #include "webkit/plugins/ppapi/ppb_video_capture_impl.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 155 matching lines @@
 
 void PPB_VideoCapture_Impl::OnInitialized(media::VideoCapture* capture,
                                           bool succeeded) {
   DCHECK(capture == platform_video_capture_.get());
 
   OnOpenComplete(succeeded ? PP_OK : PP_ERROR_FAILED);
 }
 
 int32_t PPB_VideoCapture_Impl::InternalEnumerateDevices(
     PP_Resource* devices,
-    PP_CompletionCallback callback) {
+    const PP_CompletionCallback& callback) {
   PluginInstance* instance = ResourceHelper::GetPluginInstance(this);
   if (!instance)
     return PP_ERROR_FAILED;
 
   devices_ = devices;
   enumerate_devices_callback_ = new TrackedCallback(this, callback);
   instance->delegate()->EnumerateDevices(
       PP_DEVICETYPE_DEV_VIDEOCAPTURE,
       base::Bind(&PPB_VideoCapture_Impl::EnumerateDevicesCallbackFunc,
                  AsWeakPtr()));
   return PP_OK_COMPLETIONPENDING;
 }
 
 int32_t PPB_VideoCapture_Impl::InternalOpen(
     const std::string& device_id,
     const PP_VideoCaptureDeviceInfo_Dev& requested_info,
     uint32_t buffer_count,
-    PP_CompletionCallback callback) {
+    const PP_CompletionCallback& callback) {
   // It is able to complete synchronously if the default device is used.
   bool sync_completion = device_id.empty();
 
   if (!callback.func && !sync_completion)
     return PP_ERROR_BLOCKS_MAIN_THREAD;
 
   PluginInstance* instance = ResourceHelper::GetPluginInstance(this);
   if (!instance)
     return PP_ERROR_FAILED;
 
@@ skipping 113 matching lines @@
     : in_use(false),
       data(NULL),
       buffer() {
 }
 
 PPB_VideoCapture_Impl::BufferInfo::~BufferInfo() {
 }
 
 }  // namespace ppapi
 }  // namespace webkit