New TimeToFirstURLJob* navigation metrics now work with PlzNavigate.

content/browser/frame_host/navigator.h

 // Copyright 2013 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_FRAME_HOST_NAVIGATOR_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "content/common/content_export.h"
@@ skipping 125 matching lines @@
   // PlzNavigate
   // Cancel a NavigationRequest for |frame_tree_node|. Called when
   // |frame_tree_node| is destroyed.
   virtual void CancelNavigation(FrameTreeNode* frame_tree_node) {}
 
   // Called when the first resource request for a given navigation is executed
   // so that it can be tracked into an histogram.
   virtual void LogResourceRequestTime(
     base::TimeTicks timestamp, const GURL& url) {};
 
+  // PlzNavigate
+  // Called when ResourceDispacherHostImpl is about to begin working on a

[clamy, 2015/01/27 12:35:04]

s/is about to begin working/has started working

[carlosk, 2015/01/27 17:12:03]

Done.

+  // navigation request, right before the first network request is made so that
+  // the timestamp can be recorded into an histogram.
+  virtual void LogAboutToBeginNavigation(base::TimeTicks timestamp) {};

[carlosk, 2015/01/26 19:54:01]

I switched the method name here, adding the Log prefix because for Navigator the
logging is the purpose of this call.

For the whole loader hierarchy what matters is the more generic notification
that the navigation is about to begin, hence it not having the same prefix.

[clamy, 2015/01/27 12:35:03]

Acknowledged.

+
   // Called to record the time it took to execute the before unload hook for the
   // current navigation.
   virtual void LogBeforeUnloadTime(
       const base::TimeTicks& renderer_before_unload_start_time,
       const base::TimeTicks& renderer_before_unload_end_time) {}
 
   // PlzNavigate
   // Returns whether there is an ongoing navigation waiting for the BeforeUnload
   // event to execute in the renderer process.
   virtual bool IsWaitingForBeforeUnloadACK(FrameTreeNode* frame_tree_node);
 
  protected:
   friend class base::RefCounted<Navigator>;
   virtual ~Navigator() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_H_