Update {virtual,override} to follow C++11 style in ppapi.

ppapi/proxy/flash_drm_resource.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_PROXY_FLASH_DRM_RESOURCE_H_
 #define PPAPI_PROXY_FLASH_DRM_RESOURCE_H_
 
 #include "ppapi/proxy/plugin_resource.h"
 #include "ppapi/proxy/ppapi_proxy_export.h"
 #include "ppapi/shared_impl/tracked_callback.h"
 #include "ppapi/thunk/ppb_flash_drm_api.h"
 
 namespace ppapi {
 struct FileRefCreateInfo;
 }
 
 namespace ppapi {
 namespace proxy {
 
 class FlashDRMResource
     : public PluginResource,
       public thunk::PPB_Flash_DRM_API {
  public:
   FlashDRMResource(Connection connection,
                    PP_Instance instance);
-  virtual ~FlashDRMResource();
+  ~FlashDRMResource() override;
 
   // Resource override.
-  virtual thunk::PPB_Flash_DRM_API* AsPPB_Flash_DRM_API() override;
+  thunk::PPB_Flash_DRM_API* AsPPB_Flash_DRM_API() override;
 
   // PPB_Flash_DRM_API implementation.
-  virtual int32_t GetDeviceID(PP_Var* id,
-                              scoped_refptr<TrackedCallback> callback) override;
-  virtual PP_Bool GetHmonitor(int64_t* hmonitor) override;
-  virtual int32_t GetVoucherFile(
+  int32_t GetDeviceID(PP_Var* id,
+                      scoped_refptr<TrackedCallback> callback) override;
+  PP_Bool GetHmonitor(int64_t* hmonitor) override;
+  int32_t GetVoucherFile(
       PP_Resource* file_ref,
       scoped_refptr<TrackedCallback> callback) override;
-  virtual int32_t MonitorIsExternal(
+  int32_t MonitorIsExternal(
       PP_Bool* is_external,
       scoped_refptr<TrackedCallback> callback) override;
 
  private:
   void OnPluginMsgGetDeviceIDReply(PP_Var* dest,
                                    scoped_refptr<TrackedCallback> callback,
                                    const ResourceMessageReplyParams& params,
                                    const std::string& id);
   void OnPluginMsgGetVoucherFileReply(PP_Resource* dest,
                                       scoped_refptr<TrackedCallback> callback,
                                       const ResourceMessageReplyParams& params,
                                       const FileRefCreateInfo& file_info);
   void OnPluginMsgMonitorIsExternalReply(
       PP_Bool* dest,
       scoped_refptr<TrackedCallback> callback,
       const ResourceMessageReplyParams& params,
       PP_Bool is_external);
 
   DISALLOW_COPY_AND_ASSIGN(FlashDRMResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_FLASH_DRM_RESOURCE_H_