Update the CHECK in 'NavigationHandleImpl::GetRenderFrameHost()'

content/browser/frame_host/navigation_handle_impl.cc

Index: content/browser/frame_host/navigation_handle_impl.cc
diff --git a/content/browser/frame_host/navigation_handle_impl.cc b/content/browser/frame_host/navigation_handle_impl.cc
index a6267b6e28471d552d15d095eec511c5f3964c4c..3969fb3a653174587ea8fbe1c0968bf45aef235c 100644
--- a/content/browser/frame_host/navigation_handle_impl.cc
+++ b/content/browser/frame_host/navigation_handle_impl.cc
@@ -183,9 +183,9 @@ net::Error NavigationHandleImpl::GetNetErrorCode() {
 }
 
 RenderFrameHostImpl* NavigationHandleImpl::GetRenderFrameHost() {
-  CHECK(state_ >= READY_TO_COMMIT)
-      << "This accessor should only be called "
-         "after the navigation is ready to commit.";
+  CHECK_GE(state_, WILL_PROCESS_RESPONSE)
+      << "This accessor should only be called after a response has been "
+         "delivered for processing.";

[nasko, 2016/06/24 16:08:41]

I'm afraid of making this change. Mainly because with the current navigation
path calling this at WillProcessResponse can give you the wrong RenderFrameHost.
If used to update some state, it will be incorrect.

I was actually thinking about this on my travel back from BlinkOn. There are two
types of cases that I am aware of that will call this:
* XFO throttle, which doesn't actually care about the RFH itself. It cares to
check the ancestor chain. In that case, we can expose the parent RFH as a
specific method one can call on the handle. 
* Code which needs to setup state on the RFH before it has committed. This type
of code should use ReadyToCommitNavigation. Yes, it doesn't currently work in
default navigation code, but we are working on getting it there.

So overall, I think we can do this change, but put a TODO to remove it once
ReadyToCommitNavigation is supported in the current navigation code.

   return render_frame_host_;
 }