Plumb whether or not a frame is in shadow DOM to the embedder.

Source/web/RemoteFrameClientImpl.h

Index: Source/web/RemoteFrameClientImpl.h
diff --git a/Source/web/RemoteFrameClientImpl.h b/Source/web/RemoteFrameClientImpl.h
index c1e189677ec51535f967a64416e0dd81eb353db0..2889464a27a64d1b68747e4a0548e887016e87f7 100644
--- a/Source/web/RemoteFrameClientImpl.h
+++ b/Source/web/RemoteFrameClientImpl.h
@@ -10,24 +10,22 @@
 namespace blink {
 class WebRemoteFrameImpl;
 
-class RemoteFrameClientImpl : public RemoteFrameClient {
+class RemoteFrameClientImpl final : public RemoteFrameClient {
 public:
     explicit RemoteFrameClientImpl(WebRemoteFrameImpl*);
 
     // FrameClient overrides:
+    virtual bool inShadowTree() const override;
     virtual void willBeDetached() override;
     virtual void detached() override;
-
     virtual Frame* opener() const override;
     virtual void setOpener(Frame*) override;
-
     virtual Frame* parent() const override;
     virtual Frame* top() const override;
     virtual Frame* previousSibling() const override;
     virtual Frame* nextSibling() const override;
     virtual Frame* firstChild() const override;
     virtual Frame* lastChild() const override;
-
     virtual bool willCheckAndDispatchMessageEvent(SecurityOrigin*, MessageEvent*, LocalFrame*) const override;
 
     // RemoteFrameClient overrides: