Use WebViewHelper::LocalMainFrame where possible.

third_party/WebKit/Source/web/tests/BrowserControlsTest.cpp

 /*
  * Copyright (C) 2015 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 109 matching lines @@
     GetWebView()->HandleInputEvent(
         GenerateEvent(WebInputEvent::kGestureScrollEnd));
   }
 
   Element* GetElementById(const WebString& id) {
     return static_cast<Element*>(
         GetWebView()->MainFrameImpl()->GetDocument().GetElementById(id));
   }
 
   WebViewBase* GetWebView() const { return helper_.WebView(); }
-  LocalFrame* GetFrame() const {
-    return helper_.WebView()->MainFrameImpl()->GetFrame();
-  }
+  LocalFrame* GetFrame() const { return helper_.LocalMainFrame()->GetFrame(); }
   VisualViewport& GetVisualViewport() const {
     return helper_.WebView()->GetPage()->GetVisualViewport();
   }
 
  private:
   std::string base_url_;
   FrameTestHelpers::WebViewHelper helper_;
 };
 
 #define EXPECT_SIZE_EQ(expected, actual)                     \
@@ skipping 928 matching lines @@
 
     // Make sure we're not adding the browser controls height to the vh units as
     // when they're locked to hidden, the ICB fills the entire viewport already.
     EXPECT_FLOAT_EQ(200.f, abs_pos->getBoundingClientRect()->height());
     EXPECT_FLOAT_EQ(200.f, fixed_pos->getBoundingClientRect()->height());
     EXPECT_EQ(400, GetFrame()->View()->ViewportSizeForViewportUnits().Height());
   }
 }
 
 }  // namespace blink