New TimeToFirstURLJob* navigation metrics now work with PlzNavigate.

content/browser/loader/navigation_url_loader_impl.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.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "content/browser/frame_host/navigation_request_info.h"
 #include "content/browser/loader/navigation_url_loader_delegate.h"
@@ skipping 55 matching lines @@
 
   delegate_->OnResponseStarted(response, body.Pass());
 }
 
 void NavigationURLLoaderImpl::NotifyRequestFailed(int net_error) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   delegate_->OnRequestFailed(net_error);
 }
 
+void NavigationURLLoaderImpl::AboutToBeginNavigation(
+    base::TimeTicks timestamp) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  delegate_->AboutToBeginNavigation(timestamp);
+}
+
 }  // namespace content