Standardize usage of virtual/override/final in mojo/

mojo/cc/context_provider_mojo.h

Index: mojo/cc/context_provider_mojo.h
diff --git a/mojo/cc/context_provider_mojo.h b/mojo/cc/context_provider_mojo.h
index 294bd5decedd894f66f4c283c9efbf131ccaea75..014b9734e0fe9a0e33899c519773fb01d348b7bf 100644
--- a/mojo/cc/context_provider_mojo.h
+++ b/mojo/cc/context_provider_mojo.h
@@ -17,24 +17,24 @@ class ContextProviderMojo : public cc::ContextProvider {
   explicit ContextProviderMojo(ScopedMessagePipeHandle command_buffer_handle);
 
   // cc::ContextProvider implementation.
-  virtual bool BindToCurrentThread() override;
-  virtual gpu::gles2::GLES2Interface* ContextGL() override;
-  virtual gpu::ContextSupport* ContextSupport() override;
-  virtual class GrContext* GrContext() override;
-  virtual Capabilities ContextCapabilities() override;
-  virtual bool IsContextLost() override;
-  virtual void VerifyContexts() override {}
-  virtual void DeleteCachedResources() override {}
-  virtual bool DestroyedOnMainThread() override;
-  virtual void SetLostContextCallback(
+  bool BindToCurrentThread() override;
+  gpu::gles2::GLES2Interface* ContextGL() override;
+  gpu::ContextSupport* ContextSupport() override;
+  class GrContext* GrContext() override;
+  Capabilities ContextCapabilities() override;
+  bool IsContextLost() override;
+  void VerifyContexts() override {}
+  void DeleteCachedResources() override {}
+  bool DestroyedOnMainThread() override;
+  void SetLostContextCallback(
       const LostContextCallback& lost_context_callback) override {}
-  virtual void SetMemoryPolicyChangedCallback(
+  void SetMemoryPolicyChangedCallback(
       const MemoryPolicyChangedCallback& memory_policy_changed_callback)
       override {}
 
  protected:
   friend class base::RefCountedThreadSafe<ContextProviderMojo>;
-  virtual ~ContextProviderMojo();
+  ~ContextProviderMojo() override;
 
  private:
   static void ContextLostThunk(void* closure) {