New TimeToFirstURLJob* navigation metrics now work with PlzNavigate.

content/browser/loader/navigation_url_loader_impl_core.h

 // 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.
 
 #ifndef CONTENT_BROWSER_LOADER_NAVIGATION_URL_LOADER_IMPL_CORE_H_
 #define CONTENT_BROWSER_LOADER_NAVIGATION_URL_LOADER_IMPL_CORE_H_
 
 #include "base/basictypes.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
 #include "content/browser/loader/navigation_url_loader_impl.h"
 
 namespace net {
 class URLRequest;
 struct RedirectInfo;
 }
 
 namespace content {
 
 class FrameTreeNode;
@@ skipping 34 matching lines @@
   void NotifyRequestRedirected(const net::RedirectInfo& redirect_info,
                                ResourceResponse* response);
 
   // Notifies |loader_| on the UI thread that the response started.
   void NotifyResponseStarted(ResourceResponse* response,
                              scoped_ptr<StreamHandle> body);
 
   // Notifies |loader_| on the UI thread that the request failed.
   void NotifyRequestFailed(int net_error);
 
+  // Notifies |loader_| on the UI thread that request is about to begin its
+  // first network request.
+  void AboutToBeginNavigation(base::TimeTicks timestamp);
+
  private:
   base::WeakPtr<NavigationURLLoaderImpl> loader_;
   NavigationResourceHandler* resource_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationURLLoaderImplCore);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_NAVIGATION_URL_LOADER_IMPL_CORE_H_