Standardize usage of virtual/override/final specifiers.

gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 #include <GLES2/gl2extchromium.h>
 
 #include "gpu/command_buffer/client/gles2_lib.h"
 #include "gpu/command_buffer/common/mailbox.h"
@@ skipping 36 matching lines @@
   glBindFramebuffer(GL_FRAMEBUFFER, old_fbo);
 
   glDeleteFramebuffers(1, &fbo);
 
   return texel;
 }
 }
 
 class GLTextureMailboxTest : public testing::Test {
  protected:
-  virtual void SetUp() {
+  void SetUp() override {
     gl1_.Initialize(GLManager::Options());
     GLManager::Options options;
     options.share_mailbox_manager = &gl1_;
     gl2_.Initialize(options);
   }
 
-  virtual void TearDown() {
+  void TearDown() override {
     gl1_.Destroy();
     gl2_.Destroy();
   }
 
   GLManager gl1_;
   GLManager gl2_;
 };
 
 TEST_F(GLTextureMailboxTest, ProduceAndConsumeTexture) {
   gl1_.MakeCurrent();
@@ skipping 370 matching lines @@
     other_gl[i].Destroy();
   }
 
   gl1_.MakeCurrent();
   glDeleteTextures(2, tex);
 }
 #endif
 
 }  // namespace gpu