Trust the renderer's same-document navigation flag if it is a same-origin nav.

content/browser/frame_host/navigation_controller_impl.cc

 // Copyright 2013 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_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 91 matching lines @@
     // NOTE(darin): This code is only needed for backwards compat.
     SetPageStateIfEmpty((*entries)[i].get());
   }
 }
 
 // See NavigationController::IsURLInPageNavigation for how this works and why.
 bool AreURLsInPageNavigation(const GURL& existing_url,
                              const GURL& new_url,
                              bool renderer_says_in_page,
                              NavigationType navigation_type) {
-  if (existing_url == new_url)
+  if (existing_url.GetOrigin() == new_url.GetOrigin())
     return renderer_says_in_page;
 
   if (!new_url.has_ref()) {
     // When going back from the ref URL to the non ref one the navigation type
     // is IN_PAGE.
     return navigation_type == NAVIGATION_TYPE_IN_PAGE;
   }
 
   url::Replacements<char> replacements;
   replacements.ClearRef();
@@ skipping 1647 matching lines @@
     }
   }
 }
 
 void NavigationControllerImpl::SetGetTimestampCallbackForTest(
     const base::Callback<base::Time()>& get_timestamp_callback) {
   get_timestamp_callback_ = get_timestamp_callback;
 }
 
 }  // namespace content