Break dependency between ChromeClient and WebViewImpl, and ChromeClientImpl.

third_party/WebKit/Source/web/WebViewImpl.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 476 matching lines @@
   WebDisplayMode DisplayMode() const override { return display_mode_; }
 
   PageScaleConstraintsSet& GetPageScaleConstraintsSet() const override;
 
   FloatSize ElasticOverscroll() const override { return elastic_overscroll_; }
 
   double LastFrameTimeMonotonic() const override {
     return last_frame_time_monotonic_;
   }
 
-  ChromeClientImpl& ChromeClient() const { return *chrome_client_impl_.Get(); }
+  class ChromeClient& ChromeClient() const override {
+    return *chrome_client_impl_.Get();
+  }
 
   // Returns the currently active WebInputMethodController which is the one
   // corresponding to the focused frame. It will return nullptr if there is no
   // focused frame, or if the there is one but it belongs to a different local
   // root.
   WebInputMethodControllerImpl* GetActiveWebInputMethodController() const;
 
   void SetLastHiddenPagePopup(WebPagePopupImpl* page_popup) override {
     last_hidden_page_popup_ = page_popup;
   }
@@ skipping 237 matching lines @@
   Persistent<ResizeViewportAnchor> resize_viewport_anchor_;
 };
 
 // We have no ways to check if the specified WebView is an instance of
 // WebViewImpl because WebViewImpl is the only implementation of WebView.
 DEFINE_TYPE_CASTS(WebViewImpl, WebView, webView, true, true);
 
 }  // namespace blink
 
 #endif