Remove unnecessary 'virtual' annotation from mojo

mojo/services/html_viewer/ax_provider_impl_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 "mojo/services/html_viewer/ax_provider_impl.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "gin/public/isolate_holder.h"
 #include "mojo/services/html_viewer/blink_platform_impl.h"
@@ skipping 15 matching lines @@
 using blink::WebViewClient;
 
 using mojo::Array;
 using mojo::AxNode;
 using mojo::AxNodePtr;
 
 namespace {
 
 class TestWebFrameClient : public WebFrameClient {
  public:
-  virtual ~TestWebFrameClient() {}
-  virtual void didStopLoading() { base::MessageLoop::current()->Quit(); }
+  ~TestWebFrameClient() override {}
+  void didStopLoading() override { base::MessageLoop::current()->Quit(); }
 };
 
 class TestWebViewClient : public WebViewClient {
  public:
-  virtual bool allowsBrokenNullLayerTreeView() const { return true; }
+  bool allowsBrokenNullLayerTreeView() const override { return true; }
   virtual ~TestWebViewClient() {}
 };
 
 class AxProviderImplTest : public testing::Test {
  public:
   AxProviderImplTest() {
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
     gin::IsolateHolder::LoadV8Snapshot();
 #endif
     blink::initialize(new html_viewer::BlinkPlatformImpl());
@@ skipping 116 matching lines @@
                              "",
                              ""));
     }
   }
 
   // TODO(aa): Test bounds.
   // TODO(aa): Test sibling ordering of foo/bar/baz.
 
   view->close();
 }