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

content/browser/frame_host/navigation_handle_impl.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/navigation_handle_impl.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "content/browser/frame_host/frame_tree_node.h"
@@ skipping 165 matching lines @@
   CHECK_NE(INITIAL, state_)
       << "This accessor should not be called before the request is started.";
   return is_external_protocol_;
 }
 
 net::Error NavigationHandleImpl::GetNetErrorCode() {
   return net_error_code_;
 }
 
 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_;
 }
 
 bool NavigationHandleImpl::IsSamePage() {
   DCHECK(state_ == DID_COMMIT || state_ == DID_COMMIT_ERROR_PAGE)
       << "This accessor should not be called before the navigation has "
          "committed.";
   return is_same_page_;
 }
 
@@ skipping 333 matching lines @@
   complete_callback_.Reset();
 
   if (!callback.is_null())
     callback.Run(result);
 
   // No code after running the callback, as it might have resulted in our
   // destruction.
 }
 
 }  // namespace content