PlzNavigate: Add metrics to understand bf navigations PLT regression

content/browser/frame_host/navigation_handle_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 
 #include "content/public/browser/navigation_handle.h"
 
 #include <stddef.h>
@@ skipping 468 matching lines @@
 
   // A list of Throttles registered for this navigation.
   std::vector<std::unique_ptr<NavigationThrottle>> throttles_;
 
   // The index of the next throttle to check.
   size_t next_index_;
 
   // The time this navigation started.
   const base::TimeTicks navigation_start_;
 
+  // The time this naviagtion was ready to commit.
+  base::TimeTicks ready_to_commit_time_;
+
   // The unique id of the corresponding NavigationEntry.
   int pending_nav_entry_id_;
 
   // The fetch request context type.
   RequestContextType request_context_type_;
 
   // The mixed content context type for potential mixed content checks.
   blink::WebMixedContentContextType mixed_content_context_type_;
 
   // This callback will be run when all throttle checks have been performed. Be
@@ skipping 79 matching lines @@
   int expected_render_process_host_id_;
 
   base::WeakPtrFactory<NavigationHandleImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_