Add CHECK failure to XSRH, to detect which tests exercise this case via a tryjob.

content/browser/loader/cross_site_resource_handler.cc

 // Copyright (c) 2012 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/loader/cross_site_resource_handler.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 78 matching lines @@
 // Returns whether a transfer is needed by doing a check on the UI thread.
 CrossSiteResourceHandler::NavigationDecision
 CheckNavigationPolicyOnUI(GURL real_url, int process_id, int render_frame_id) {
   CHECK(SiteIsolationPolicy::AreCrossProcessFramesPossible());
   RenderFrameHostImpl* rfh =
       RenderFrameHostImpl::FromID(process_id, render_frame_id);
 
   // Without a valid RFH against which to check, we must cancel the request,
   // to prevent the resource at |url| from being delivered to a potentially
   // unsuitable renderer process.
-  if (!rfh)
+  if (!rfh) {
+    CHECK(false);
     return CrossSiteResourceHandler::NavigationDecision::CANCEL_REQUEST;
+  }
 
   RenderFrameHostManager* manager = rfh->frame_tree_node()->render_manager();
   if (manager->IsRendererTransferNeededForNavigation(rfh, real_url))
     return CrossSiteResourceHandler::NavigationDecision::TRANSFER_REQUIRED;
   else
     return CrossSiteResourceHandler::NavigationDecision::USE_EXISTING_RENDERER;
 }
 
 }  // namespace
 
@@ skipping 270 matching lines @@
     controller()->Resume();
   }
 }
 
 void CrossSiteResourceHandler::OnDidDefer() {
   did_defer_ = true;
   request()->LogBlockedBy("CrossSiteResourceHandler");
 }
 
 }  // namespace content