Detach old frame on WebFrame::swap.

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 65ad70fa4e96778964582b7472fe7910f3a0665e..4b639ec3da617308052bb2428a87f968774112ac 100644
--- a/content/renderer/render_frame_proxy.h
+++ b/content/renderer/render_frame_proxy.h
@@ -19,6 +19,7 @@ struct FrameMsg_CompositorFrameSwapped_Params;
 
 namespace blink {
 class WebInputEvent;
+enum class WebDetachReason;
 }
 
 namespace content {
@@ -112,7 +113,9 @@ class CONTENT_EXPORT RenderFrameProxy
   blink::WebRemoteFrame* web_frame() { return web_frame_; }
 
   // blink::WebRemoteFrameClient implementation:
+  // TODO(lfg): Remove this method once the blink patch lands.
   virtual void frameDetached();
+  virtual void frameDetached(blink::WebDetachReason reason);
   virtual void postMessageEvent(
       blink::WebLocalFrame* sourceFrame,
       blink::WebRemoteFrame* targetFrame,