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

ppapi/proxy/ppb_message_loop_proxy.h

Index: ppapi/proxy/ppb_message_loop_proxy.h
diff --git a/ppapi/proxy/ppb_message_loop_proxy.h b/ppapi/proxy/ppb_message_loop_proxy.h
index 73df5f1cb2841f84d4ea17056fb4fd57d4803a14..0aa07fe3b5f1e92c47b591b99830d7b36c8f09b4 100644
--- a/ppapi/proxy/ppb_message_loop_proxy.h
+++ b/ppapi/proxy/ppb_message_loop_proxy.h
@@ -26,17 +26,16 @@ class PPAPI_PROXY_EXPORT MessageLoopResource : public MessageLoopShared {
   // Construct the one MessageLoopResource for the main thread. This must be
   // invoked on the main thread.
   explicit MessageLoopResource(ForMainThread);
-  virtual ~MessageLoopResource();
+  ~MessageLoopResource() override;
 
   // Resource overrides.
-  virtual thunk::PPB_MessageLoop_API* AsPPB_MessageLoop_API() override;
+  thunk::PPB_MessageLoop_API* AsPPB_MessageLoop_API() override;
 
   // PPB_MessageLoop_API implementation.
-  virtual int32_t AttachToCurrentThread() override;
-  virtual int32_t Run() override;
-  virtual int32_t PostWork(PP_CompletionCallback callback,
-                           int64_t delay_ms) override;
-  virtual int32_t PostQuit(PP_Bool should_destroy) override;
+  int32_t AttachToCurrentThread() override;
+  int32_t Run() override;
+  int32_t PostWork(PP_CompletionCallback callback, int64_t delay_ms) override;
+  int32_t PostQuit(PP_Bool should_destroy) override;
 
   static MessageLoopResource* GetCurrent();
   void DetachFromThread();
@@ -69,11 +68,11 @@ class PPAPI_PROXY_EXPORT MessageLoopResource : public MessageLoopShared {
   // NOTE: The given closure will be run *WITHOUT* acquiring the Proxy lock.
   //       This only makes sense for user code and completely thread-safe
   //       proxy operations (e.g., MessageLoop::QuitClosure).
-  virtual void PostClosure(const tracked_objects::Location& from_here,
-                           const base::Closure& closure,
-                           int64 delay_ms) override;
-  virtual base::MessageLoopProxy* GetMessageLoopProxy() override;
-  virtual bool CurrentlyHandlingBlockingMessage() override;
+  void PostClosure(const tracked_objects::Location& from_here,
+                   const base::Closure& closure,
+                   int64 delay_ms) override;
+  base::MessageLoopProxy* GetMessageLoopProxy() override;
+  bool CurrentlyHandlingBlockingMessage() override;
 
   // TLS destructor function.
   static void ReleaseMessageLoop(void* value);