Remove SiteIsolationPolicy::IsSwappedOutStateForbidden().

content/renderer/render_frame_proxy.h

Index: content/renderer/render_frame_proxy.h
diff --git a/content/renderer/render_frame_proxy.h b/content/renderer/render_frame_proxy.h
index 5986e16199b45877ef1547f40e7112afa4797bda..854b1a971ea21d22f897d650eebfbcd74ff2881f 100644
--- a/content/renderer/render_frame_proxy.h
+++ b/content/renderer/render_frame_proxy.h
@@ -115,12 +115,6 @@ class CONTENT_EXPORT RenderFrameProxy
   // RenderFrameProxy's WebRemoteFrame.
   void SetReplicatedState(const FrameReplicationState& state);
 
-  // Navigating a top-level frame cross-process does not swap the WebLocalFrame
-  // for a WebRemoteFrame in the frame tree. In this case, this WebRemoteFrame
-  // is not attached to the frame tree and there is no blink::Frame associated
-  // with it, so it is not in state where most operations on it will succeed.
-  bool IsMainFrameDetachedFromTree() const;
-
   int routing_id() { return routing_id_; }
   RenderViewImpl* render_view() { return render_view_; }
   blink::WebRemoteFrame* web_frame() { return web_frame_; }