Remove unnecessary 'virtual' annotation from mojo

mojo/services/html_viewer/ax_provider_impl_unittest.cc

Index: mojo/services/html_viewer/ax_provider_impl_unittest.cc
diff --git a/mojo/services/html_viewer/ax_provider_impl_unittest.cc b/mojo/services/html_viewer/ax_provider_impl_unittest.cc
index b001e2512db44171d84726fe9fd6ac45fd6fce52..a7ffac236de7d823bf1b6eaefdcd53a2a44701be 100644
--- a/mojo/services/html_viewer/ax_provider_impl_unittest.cc
+++ b/mojo/services/html_viewer/ax_provider_impl_unittest.cc
@@ -33,13 +33,13 @@ 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() {}
 };