Switch the inheritance of WebViewClient from WebWidgetClient to protected.

third_party/WebKit/Source/web/ChromeClientImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * 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.
@@ skipping 547 matching lines @@
     }
 }
 
 IntRect ChromeClientImpl::viewportToScreen(const IntRect& rectInViewport, const Widget* widget) const
 {
     WebRect screenRect(rectInViewport);
 
     DCHECK(widget->isFrameView());
     const FrameView* view = toFrameView(widget);
     LocalFrame* frame = view->frame().localFrameRoot();
-    WebWidgetClient* client = nullptr;
 
-    // TODO(kenrb): Consolidate this to a single case when WebViewFrameWidget refactor is complete.
-    if (WebLocalFrameImpl::fromFrame(frame) && WebLocalFrameImpl::fromFrame(frame)->frameWidget() && WebLocalFrameImpl::fromFrame(frame)->frameWidget()->forSubframe())
-        client = toWebFrameWidgetImpl(WebLocalFrameImpl::fromFrame(frame)->frameWidget())->client();
-    else
-        client = m_webView->client();
+    WebWidgetClient* client = WebLocalFrameImpl::fromFrame(frame)->frameWidget()->client();
 
     if (client) {

[dcheng, 2016/04/28 17:30:21]

Out of curiosity, does anyone actually pass a null client?

[lfg, 2016/04/28 17:43:57]

I haven't checked, but this should never happen, since the localRoot should
always have a widget. I'll try to remove the null check and send a separate CL
for that.

         client->convertViewportToWindow(&screenRect);
         WebRect windowRect = client->windowRect();
         screenRect.x += windowRect.x;
         screenRect.y += windowRect.y;
     }
+
     return screenRect;
 }
 
 float ChromeClientImpl::windowToViewportScalar(const float scalarValue) const
 {
     if (!m_webView->client())
         return scalarValue;
     WebFloatRect viewportRect(0, 0, scalarValue, 0);
     m_webView->client()->convertWindowToViewport(&viewportRect);
     return viewportRect.width;
@@ skipping 526 matching lines @@
 {
     return adoptPtr(m_webView->scheduler()->createFrameScheduler(blameContext).release());
 }
 
 double ChromeClientImpl::lastFrameTimeMonotonic() const
 {
     return m_webView->lastFrameTimeMonotonic();
 }
 
 } // namespace blink