Prevent the destruction of WebContents in NavigationThrottle methods

content/browser/loader/navigation_resource_throttle.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/loader/navigation_resource_throttle.h"
 
 #include "base/callback.h"
 #include "content/browser/frame_host/navigation_handle_impl.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/public/browser/resource_context.h"
 #include "content/public/browser/resource_controller.h"
 #include "content/public/browser/resource_request_info.h"
 #include "content/public/common/referrer.h"
 #include "net/url_request/redirect_info.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_job_factory.h"
 #include "ui/base/page_transition_types.h"
 
 namespace content {
 
 namespace {
 typedef base::Callback<void(NavigationThrottle::ThrottleCheckResult)>
     UIChecksPerformedCallback;
 
 void SendCheckResultToIOThread(UIChecksPerformedCallback callback,
                                NavigationThrottle::ThrottleCheckResult result) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  CHECK(result != NavigationThrottle::DEFER);
+  CHECK(result != NavigationThrottle::DEFER &&
+        result != NavigationThrottle::DESTROYED);
   BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
                           base::Bind(callback, result));
 }
 
 void CheckWillStartRequestOnUIThread(UIChecksPerformedCallback callback,
                                      int render_process_id,
                                      int render_frame_host_id,
                                      bool is_post,
                                      const Referrer& sanitized_referrer,
                                      bool has_user_gesture,
@@ skipping 121 matching lines @@
     NavigationThrottle::ThrottleCheckResult result) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (result == NavigationThrottle::CANCEL_AND_IGNORE) {
     controller()->CancelAndIgnore();
   } else {
     controller()->Resume();
   }
 }
 
 }  // namespace content