Standardize usage of virtual/override/final in mojo/

mojo/gles2/gles2_context.h

Index: mojo/gles2/gles2_context.h
diff --git a/mojo/gles2/gles2_context.h b/mojo/gles2/gles2_context.h
index 0bbb7548ffc40c8d1b64f2b86fdfd700680d4942..7dd108553a902064d3f9375c9c398008ca9056e5 100644
--- a/mojo/gles2/gles2_context.h
+++ b/mojo/gles2/gles2_context.h
@@ -31,7 +31,7 @@ class GLES2Context : public CommandBufferDelegate,
                         ScopedMessagePipeHandle command_buffer_handle,
                         MojoGLES2ContextLost lost_callback,
                         void* closure);
-  virtual ~GLES2Context();
+  ~GLES2Context() override;
   bool Initialize();
 
   gpu::gles2::GLES2Interface* interface() const {
@@ -40,7 +40,7 @@ class GLES2Context : public CommandBufferDelegate,
   gpu::ContextSupport* context_support() const { return implementation_.get(); }
 
  private:
-  virtual void ContextLost() override;
+  void ContextLost() override;
 
   CommandBufferClientImpl command_buffer_;
   scoped_ptr<gpu::gles2::GLES2CmdHelper> gles2_helper_;