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

ppapi/proxy/ppb_flash_message_loop_proxy.cc

Index: ppapi/proxy/ppb_flash_message_loop_proxy.cc
diff --git a/ppapi/proxy/ppb_flash_message_loop_proxy.cc b/ppapi/proxy/ppb_flash_message_loop_proxy.cc
index e4e92e9d3e7dd3682b6d14a902b8bc4ca2dfe409..1b332185293a5b5be7cbac8f908edf00a09d1004 100644
--- a/ppapi/proxy/ppb_flash_message_loop_proxy.cc
+++ b/ppapi/proxy/ppb_flash_message_loop_proxy.cc
@@ -24,16 +24,15 @@ namespace {
 class FlashMessageLoop : public PPB_Flash_MessageLoop_API, public Resource {
  public:
   explicit FlashMessageLoop(const HostResource& resource);
-  virtual ~FlashMessageLoop();
+  ~FlashMessageLoop() override;
 
   // Resource overrides.
-  virtual PPB_Flash_MessageLoop_API* AsPPB_Flash_MessageLoop_API() override;
+  PPB_Flash_MessageLoop_API* AsPPB_Flash_MessageLoop_API() override;
 
   // PPB_Flash_MesssageLoop_API implementation.
-  virtual int32_t Run() override;
-  virtual void Quit() override;
-  virtual void RunFromHostProxy(
-      const RunFromHostProxyCallback& callback) override;
+  int32_t Run() override;
+  void Quit() override;
+  void RunFromHostProxy(const RunFromHostProxyCallback& callback) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlashMessageLoop);