PlzNavigate: fix crash in unit_tests

content/browser/loader/navigation_url_loader_impl_core.cc

 // Copyright 2014 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_url_loader_impl_core.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/time/time.h"
 #include "content/browser/frame_host/navigation_request_info.h"
@@ skipping 29 matching lines @@
     ResourceContext* resource_context,
     ServiceWorkerNavigationHandleCore* service_worker_handle_core,
     scoped_ptr<NavigationRequestInfo> request_info) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&NavigationURLLoaderImpl::NotifyRequestStarted, loader_,
                  base::TimeTicks::Now()));
 
-  ResourceDispatcherHostImpl::Get()->BeginNavigationRequest(
-      resource_context, *request_info, this, service_worker_handle_core);
+  // The ResourceDispatcherHostImpl can be null in unit tests.
+  if (ResourceDispatcherHostImpl::Get()) {

[nasko, 2015/12/03 15:10:27]

Interesting. If we hit this in real code (for some reason), it means the browser
won't be able to navigate, right? I wonder if there is some way to detect
running in test environment.

[clamy, 2015/12/03 16:15:02]

Mm not sure. It's not a change from the current situation though: if you don't
have a ResourceDispatcherHostImpl you can't handle the ResourceRequest from the
renderer.

+    ResourceDispatcherHostImpl::Get()->BeginNavigationRequest(
+        resource_context, *request_info, this, service_worker_handle_core);
+  }
 }
 
 void NavigationURLLoaderImplCore::FollowRedirect() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   if (resource_handler_)
     resource_handler_->FollowRedirect();
 }
 
 void NavigationURLLoaderImplCore::NotifyRequestRedirected(
@@ skipping 36 matching lines @@
                                                       int net_error) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&NavigationURLLoaderImpl::NotifyRequestFailed, loader_,
                  in_cache, net_error));
 }
 
 }  // namespace content