Coverity: Fix several pass-by-values.

ppapi/shared_impl/ppb_video_capture_shared.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_SHARED_IMPL_PPB_VIDEO_CAPTURE_SHARED_H_
 #define PPAPI_SHARED_IMPL_PPB_VIDEO_CAPTURE_SHARED_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/tracked_callback.h"
 #include "ppapi/thunk/ppb_video_capture_api.h"
 
 namespace ppapi {
 
 class PPAPI_SHARED_EXPORT PPB_VideoCapture_Shared
     : public Resource,
       NON_EXPORTED_BASE(public thunk::PPB_VideoCapture_API) {
  public:
   explicit PPB_VideoCapture_Shared(PP_Instance instance);
   explicit PPB_VideoCapture_Shared(const HostResource& host_resource);
   virtual ~PPB_VideoCapture_Shared();
 
-  // Resource overrides.
+  // Resource implementation.
   virtual thunk::PPB_VideoCapture_API* AsPPB_VideoCapture_API() OVERRIDE;
 
   // PPB_VideoCapture_API implementation.
-  virtual int32_t EnumerateDevices(PP_Resource* devices,
-                                   PP_CompletionCallback callback) OVERRIDE;
+  virtual int32_t EnumerateDevices(
+      PP_Resource* devices,
+      const PP_CompletionCallback& callback) OVERRIDE;
   virtual int32_t Open(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 StartCapture() OVERRIDE;
   virtual int32_t ReuseBuffer(uint32_t buffer) OVERRIDE;
   virtual int32_t StopCapture() OVERRIDE;
   virtual void Close() OVERRIDE;
   virtual int32_t StartCapture0_1(
       const PP_VideoCaptureDeviceInfo_Dev& requested_info,
       uint32_t buffer_count) OVERRIDE;
   virtual const std::vector<DeviceRefData>& GetDeviceRefData() const OVERRIDE;
 
   void OnEnumerateDevicesComplete(int32_t result,
                                   const std::vector<DeviceRefData>& devices);
   void OnOpenComplete(int32_t result);
 
  protected:
   enum OpenState {
     BEFORE_OPEN,
     OPENED,
     CLOSED
   };
 
   // Subclasses should implement these methods to do impl- and proxy-specific
   // work.
-  virtual int32_t InternalEnumerateDevices(PP_Resource* devices,
-                                           PP_CompletionCallback callback) = 0;
+  virtual int32_t InternalEnumerateDevices(
+      PP_Resource* devices,
+      const PP_CompletionCallback& callback) = 0;
   virtual int32_t InternalOpen(
       const std::string& device_id,
       const PP_VideoCaptureDeviceInfo_Dev& requested_info,
       uint32_t buffer_count,
-      PP_CompletionCallback callback) = 0;
+      const PP_CompletionCallback& callback) = 0;
   virtual int32_t InternalStartCapture() = 0;
   virtual int32_t InternalReuseBuffer(uint32_t buffer) = 0;
   virtual int32_t InternalStopCapture() = 0;
   virtual void InternalClose() = 0;
   virtual int32_t InternalStartCapture0_1(
       const PP_VideoCaptureDeviceInfo_Dev& requested_info,
       uint32_t buffer_count) = 0;
   virtual const std::vector<DeviceRefData>& InternalGetDeviceRefData(
       ) const = 0;
 
@@ skipping 14 matching lines @@
 
   ResourceObjectType resource_object_type_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PPB_VideoCapture_Shared);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_PPB_VIDEO_CAPTURE_SHARED_H_