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

ppapi/proxy/isolated_file_system_private_resource.h

Index: ppapi/proxy/isolated_file_system_private_resource.h
diff --git a/ppapi/proxy/isolated_file_system_private_resource.h b/ppapi/proxy/isolated_file_system_private_resource.h
index 4f826fe7302349366152f1f3063d7759c0e7abca..55ff23e9af70cf53f87046f5c98e72a099cfbb6f 100644
--- a/ppapi/proxy/isolated_file_system_private_resource.h
+++ b/ppapi/proxy/isolated_file_system_private_resource.h
@@ -41,17 +41,17 @@ class PPAPI_PROXY_EXPORT IsolatedFileSystemPrivateResource
  public:
   IsolatedFileSystemPrivateResource(
       Connection connection, PP_Instance instance);
-  virtual ~IsolatedFileSystemPrivateResource();
+  ~IsolatedFileSystemPrivateResource() override;
 
   // Resource overrides.
-  virtual thunk::PPB_IsolatedFileSystem_Private_API*
+  thunk::PPB_IsolatedFileSystem_Private_API*
       AsPPB_IsolatedFileSystem_Private_API() override;
 
   // PPB_IsolatedFileSystem_Private_API implementation.
-  virtual int32_t Open(PP_Instance instance,
-                       PP_IsolatedFileSystemType_Private type,
-                       PP_Resource* file_system_resource,
-                       scoped_refptr<TrackedCallback> callback) override;
+  int32_t Open(PP_Instance instance,
+               PP_IsolatedFileSystemType_Private type,
+               PP_Resource* file_system_resource,
+               scoped_refptr<TrackedCallback> callback) override;
 
  private:
   void OnBrowserOpenComplete(PP_IsolatedFileSystemType_Private type,