Provide downcasts for WebLocalFrameBase using DEFINE_TYPE_CASTS macro.

third_party/WebKit/Source/web/WebLocalFrameImpl.h

Index: third_party/WebKit/Source/web/WebLocalFrameImpl.h
diff --git a/third_party/WebKit/Source/web/WebLocalFrameImpl.h b/third_party/WebKit/Source/web/WebLocalFrameImpl.h
index c49733980caaaaa11770f7a2c3f7857f50910ef0..9ac95a81c2735e8e6c211891b0cf2b3070bb4c12 100644
--- a/third_party/WebKit/Source/web/WebLocalFrameImpl.h
+++ b/third_party/WebKit/Source/web/WebLocalFrameImpl.h
@@ -320,7 +320,7 @@ class WEB_EXPORT WebLocalFrameImpl final
                             WebString& clip_html) override;
 
   void InitializeCoreFrame(Page&, FrameOwner*, const AtomicString& name);
-  LocalFrame* GetFrame() const { return frame_.Get(); }
+  LocalFrame* GetFrame() const override { return frame_.Get(); }
 
   void WillBeDetached();
   void WillDetachParent();
@@ -362,7 +362,7 @@ class WEB_EXPORT WebLocalFrameImpl final
 
   WebViewBase* ViewImpl() const override;
 
-  FrameView* GetFrameView() const {
+  FrameView* GetFrameView() const override {
     return GetFrame() ? GetFrame()->View() : 0;
   }