Invalidate the previous frame when the window object is cleared.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index b99f8a0d556e9858c64ce244be4d0773e57d4f08..42e4ea5b270cf854a2bdfe9330097bd54c526ce0 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -2357,6 +2357,13 @@ void RenderFrameImpl::didCommitProvisionalLoad(
   UpdateEncoding(frame, frame->view()->pageEncoding().utf8());
 }
 
+void RenderFrameImpl::didCreateNewDocument(blink::WebLocalFrame* frame) {
+  DCHECK(!frame_ || frame_ == frame);

[dcheng, 2014/11/11 16:50:16]

This assert should be more aggressive. We should never call this and pass a null
frame parameter.

[robwu, 2014/11/11 21:43:59]

This DCHECK does not test whether the passed-in pointer is a non-null pointer,
but it shows that frame ought to be equal to |frame_| if set.
This whole class assumes that the passed-in WebLocalFrame* pointer is non-null,
so I don't think that we need a CHECK(!frame);
If you look at src/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp, it
becomes obvious that that class also assumes that m_webFrame is always non-null,
so again I see no point im adding a stronger assertion here.

+
+  FOR_EACH_OBSERVER(RenderViewObserver, render_view_->observers(),
+                    DidCreateNewDocument(frame));
+}
+
 void RenderFrameImpl::didClearWindowObject(blink::WebLocalFrame* frame) {
   DCHECK(!frame_ || frame_ == frame);
   // TODO(nasko): Move implementation here. Needed state: