Enforce marking "override" for functions overriding Blink.

content/child/webthemeengine_impl_android.h

Index: content/child/webthemeengine_impl_android.h
diff --git a/content/child/webthemeengine_impl_android.h b/content/child/webthemeengine_impl_android.h
index e641a6043ae69f1b5b49f1348e661aa8bdee8fde..3483ab5f2ce88e531a0477bac145c792d6e543aa 100644
--- a/content/child/webthemeengine_impl_android.h
+++ b/content/child/webthemeengine_impl_android.h
@@ -12,13 +12,12 @@ namespace content {
 class WebThemeEngineImpl : public blink::WebThemeEngine {
  public:
   // WebThemeEngine methods:
-  virtual blink::WebSize getSize(blink::WebThemeEngine::Part);
-  virtual void paint(
-      blink::WebCanvas* canvas,
-      blink::WebThemeEngine::Part part,
-      blink::WebThemeEngine::State state,
-      const blink::WebRect& rect,
-      const blink::WebThemeEngine::ExtraParams* extra_params);
+  blink::WebSize getSize(blink::WebThemeEngine::Part) override;
+  void paint(blink::WebCanvas* canvas,
+             blink::WebThemeEngine::Part part,
+             blink::WebThemeEngine::State state,
+             const blink::WebRect& rect,
+             const blink::WebThemeEngine::ExtraParams* extra_params) override;
 };
 
 }  // namespace content