Remove unnecessary 'virtual' annotation from mojo

mojo/services/html_viewer/test_blink_platform_impl.h

 // 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.
 
 #ifndef MOJO_SERVICES_HTML_VIEWER_TEST_BLINK_PLATFORM_IMPL_H_
 #define MOJO_SERVICES_HTML_VIEWER_TEST_BLINK_PLATFORM_IMPL_H_
 
 #include "mojo/services/html_viewer/blink_platform_impl.h"
 
 #include "third_party/WebKit/public/platform/WebClipboard.h"
 #include "third_party/WebKit/public/platform/WebCookieJar.h"
 
 namespace html_viewer {
 
 class TestBlinkPlatformImpl : public BlinkPlatformImpl {
  public:
   TestBlinkPlatformImpl();
-  virtual ~TestBlinkPlatformImpl();
+  ~TestBlinkPlatformImpl() override;
 
  private:
   // blink::Platform methods:
-  virtual blink::WebCookieJar* cookieJar();
-  virtual blink::WebClipboard* clipboard();
+  blink::WebCookieJar* cookieJar() override;
+  blink::WebClipboard* clipboard() override;
 
   blink::WebClipboard clipboard_;
   blink::WebCookieJar cookie_jar_;
 };
 
 }  // namespace html_viewer
 
 #endif  // MOJO_SERVICES_HTML_VIEWER_TEST_BLINK_PLATFORM_IMPL_H_