Provide a way to obtain WebLocalFrameBase from a LocalFrame.

third_party/WebKit/Source/core/frame/WebLocalFrameBase.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.#ifndef WebViewBase_h
 
 #ifndef WebLocalFrameBase_h
 #define WebLocalFrameBase_h
 
+#include "core/CoreExport.h"
 #include "public/web/WebLocalFrame.h"
 
 namespace blink {
 
+class LocalFrame;
+
 // WebLocalFrameBase is a temporary class the provides a layer of abstraction
 // for WebLocalFrameImpl. Mehtods that are declared public in WebLocalFrameImpl
 // that are not overrides from WebLocalFrame will be declared pure virtual in
 // WebLocalFrameBase. Classes that then have a dependency on WebLocalFrameImpl
 // will then take a dependency on WebLocalFrameBase instead, so we can remove
 // cyclic dependencies in web/ and move classes from web/ into core/ or
 // modules.
 // TODO(slangley): Remove this class once WebLocalFrameImpl is in core/.
 class WebLocalFrameBase : public WebLocalFrame {
+ public:
+  CORE_EXPORT static WebLocalFrameBase* FromFrame(LocalFrame*);
+  CORE_EXPORT static WebLocalFrameBase* FromFrame(LocalFrame&);
+
  protected:
   explicit WebLocalFrameBase(WebTreeScopeType scope) : WebLocalFrame(scope) {}
 };
 }
 
 #endif  // WebLocalFrameBase_h