Create base class for common functionality of Web{Local,Remote}Frame

third_party/WebKit/public/web/WebFrame.h

Index: third_party/WebKit/public/web/WebFrame.h
diff --git a/third_party/WebKit/public/web/WebFrame.h b/third_party/WebKit/public/web/WebFrame.h
index bbecd55bcf9747ca8a88b68b7c9e2378ab36bdb9..c99c667a853d4823ac6e8474213672a8847dc9c1 100644
--- a/third_party/WebKit/public/web/WebFrame.h
+++ b/third_party/WebKit/public/web/WebFrame.h
@@ -63,6 +63,7 @@ class WebData;
 class WebDataSource;
 class WebDocument;
 class WebElement;
+class WebFrameImplBase;
 class WebLayer;
 class WebLocalFrame;
 class WebPerformance;
@@ -679,6 +680,13 @@ public:
     // text form. This is used only by layout tests.
     virtual WebString layerTreeAsText(bool showDebugInfo = false) const = 0;
 
+    virtual WebFrameImplBase* toImplBase() = 0;
+    // TODO(dcheng): Fix const-correctness issues and remove this overload.
+    virtual const WebFrameImplBase* toImplBase() const
+    {
+        return const_cast<WebFrame*>(this)->toImplBase();
+    }
+
     // Returns the frame inside a given frame or iframe element. Returns 0 if
     // the given element is not a frame, iframe or if the frame is empty.
     BLINK_EXPORT static WebFrame* fromFrameOwnerElement(const WebElement&);