Cleanup RemotePlatformLayer when disconnecting RemoteFrame.

Source/core/frame/RemoteFrame.h

Index: Source/core/frame/RemoteFrame.h
diff --git a/Source/core/frame/RemoteFrame.h b/Source/core/frame/RemoteFrame.h
index 39ace61af8150228dfc0b8368e8bc99fd28f5faf..3d913bff3c156e07f7fabb8afd3bb257effa6bd0 100644
--- a/Source/core/frame/RemoteFrame.h
+++ b/Source/core/frame/RemoteFrame.h
@@ -14,6 +14,7 @@ class Event;
 class RemoteDOMWindow;
 class RemoteFrameClient;
 class RemoteFrameView;
+class WebLayer;
 
 class RemoteFrame: public Frame {
 public:
@@ -23,18 +24,22 @@ public:
 
     // Frame overrides:
     void trace(Visitor*) override;
-    virtual bool isRemoteFrame() const override { return true; }
-    virtual DOMWindow* domWindow() const override;
-    virtual void navigate(Document& originDocument, const KURL&, bool lockBackForwardList) override;
-    virtual void reload(ReloadPolicy, ClientRedirectPolicy) override;
-    virtual void detach() override;
-    virtual RemoteSecurityContext* securityContext() const override;
+    bool isRemoteFrame() const override { return true; }
+    DOMWindow* domWindow() const override;
+    void navigate(Document& originDocument, const KURL&, bool lockBackForwardList) override;
+    void reload(ReloadPolicy, ClientRedirectPolicy) override;
+    void detach() override;
+    RemoteSecurityContext* securityContext() const override;
     void printNavigationErrorMessage(const Frame&, const char* reason) { }
+    void disconnectOwnerElement() override;
 
     // FIXME: Remove this method once we have input routing in the browser
     // process. See http://crbug.com/339659.
     void forwardInputEvent(Event*);
 
+    void setRemotePlatformLayer(WebLayer*);
+    WebLayer* remotePlatformLayer() const { return m_remotePlatformLayer; }
+
     void setView(PassRefPtrWillBeRawPtr<RemoteFrameView>);
     void createView();
 
@@ -49,6 +54,8 @@ private:
     RefPtrWillBeMember<RemoteFrameView> m_view;
     RefPtr<RemoteSecurityContext> m_securityContext;
     RefPtrWillBeMember<RemoteDOMWindow> m_domWindow;
+
+    WebLayer* m_remotePlatformLayer;
 };
 
 inline RemoteFrameView* RemoteFrame::view() const