Introduce WebFrameWidget to Blink

Source/web/WebLocalFrameImpl.h

Index: Source/web/WebLocalFrameImpl.h
diff --git a/Source/web/WebLocalFrameImpl.h b/Source/web/WebLocalFrameImpl.h
index 07abc774de53cb9174cc471422c5dee15be888e4..113ca6afec9c391f5eb644d4ec5ae7bb746716b3 100644
--- a/Source/web/WebLocalFrameImpl.h
+++ b/Source/web/WebLocalFrameImpl.h
@@ -55,6 +55,7 @@ class TextFinder;
 class WebAutofillClient;
 class WebDataSourceImpl;
 class WebFrameClient;
+class WebFrameWidgetImpl;
 class WebPerformance;
 class WebPlugin;
 class WebPluginContainerImpl;
@@ -317,6 +318,9 @@ public:
     // Returns a hit-tested VisiblePosition for the given point
     VisiblePosition visiblePositionForWindowPoint(const WebPoint&);
 
+    void setFrameWidget(WebFrameWidgetImpl*);
+    WebFrameWidgetImpl* frameWidget();
+
 #if ENABLE(OILPAN)
     void trace(Visitor*);
 #endif
@@ -340,6 +344,9 @@ private:
     // FIXME: These will need to change to WebFrame when we introduce WebFrameProxy.
     RefPtrWillBeMember<LocalFrame> m_frame;
 
+    // This is set if the frame is the root of a local frame tree, and requires a widget for rendering.
+    WebFrameWidgetImpl* m_frameWidget;
+
     WebFrameClient* m_client;
     WebAutofillClient* m_autofillClient;
     WebPermissionClient* m_permissionClient;