Provide currently_committed_url to PageLoadMetricsObservers

components/page_load_metrics/browser/page_load_metrics_observer.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 COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 #define COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include "base/macros.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
 #include "content/public/browser/navigation_handle.h"
@@ skipping 79 matching lines @@
   const PageLoadMetadata metadata;
 };
 
 // Interface for PageLoadMetrics observers. All instances of this class are
 // owned by the PageLoadTracker tracking a page load. They will be deleted after
 // calling OnComplete.
 class PageLoadMetricsObserver {
  public:
   virtual ~PageLoadMetricsObserver() {}
 
-  // The page load started, with the given navigation handle.
-  virtual void OnStart(content::NavigationHandle* navigation_handle) {}
+  // The page load started, with the given navigation handle. Note that OnStart
+  // is called for same-page navigations. Implementers of OnStart that only want
+  // to process non-same-page navigations should also check to see that the page
+  // load committed via OnCommit or committed_url in
+  // PageLoadExtraInfo. currently_committed_url contains the URL of the
+  // committed page load at the time the navigation for navigation_handle was
+  // initiated, or the empty URL if there was no committed page load at the time
+  // the navigation was initiated.
+  virtual void OnStart(content::NavigationHandle* navigation_handle,
+                       const GURL& currently_committed_url) {}
 
   // OnRedirect is triggered when a page load redirects to another URL.
   // The navigation handle holds relevant data for the navigation, but will
   // be destroyed soon after this call. Don't hold a reference to it. This can
   // be called multiple times.
   virtual void OnRedirect(content::NavigationHandle* navigation_handle) {}
 
   // OnCommit is triggered when a page load commits, i.e. when we receive the
   // first data for the request. The navigation handle holds relevant data for
   // the navigation, but will be destroyed soon after this call. Don't hold a
@@ skipping 13 matching lines @@
   // data collected over the course of the page load. If the load did not
   // receive any timing information, |timing.IsEmpty()| will be true.
   // After this call, the object will be deleted.
   virtual void OnComplete(const PageLoadTiming& timing,
                           const PageLoadExtraInfo& extra_info) {}
 };
 
 }  // namespace page_load_metrics
 
 #endif  // COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_