Prevent tracking metrics for cases such as 204s and downloads.

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/browsing_data/clear_site_data_throttle.h"
@@ skipping 203 matching lines @@
 }
 
 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_;
 }
 
 const net::HttpResponseHeaders* NavigationHandleImpl::GetResponseHeaders() {
-  DCHECK_GE(state_, WILL_REDIRECT_REQUEST);
   return response_headers_.get();
 }
 
 bool NavigationHandleImpl::HasCommitted() {
   return state_ == DID_COMMIT || state_ == DID_COMMIT_ERROR_PAGE;
 }
 
 bool NavigationHandleImpl::IsErrorPage() {
   return state_ == DID_COMMIT_ERROR_PAGE;
 }
@@ skipping 498 matching lines @@
                       throttles_to_register.end());
     throttles_to_register.weak_clear();
   }
 }
 
 bool NavigationHandleImpl::WasStartedFromContextMenu() const {
   return started_from_context_menu_;
 }
 
 }  // namespace content