[page_load_metrics] Add support for chrome:// urls and add extensions observer

chrome/browser/page_load_metrics/metrics_web_contents_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 CHROME_BROWSER_PAGE_LOAD_METRICS_METRICS_WEB_CONTENTS_OBSERVER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_METRICS_WEB_CONTENTS_OBSERVER_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 55 matching lines @@
   // sent us an IPC from a navigation we don't care about).
   ERR_IPC_WITH_NO_RELEVANT_LOAD,
 
   // Received a notification from a frame that has been navigated away from.
   ERR_IPC_FROM_WRONG_FRAME,
 
   // We received an IPC even through the last committed url from the browser
   // was not http/s. This can happen with the renderer sending IPCs for the
   // new tab page. This will often come paired with
   // ERR_IPC_WITH_NO_RELEVANT_LOAD.
+  //
+  // DEPRECATED: our IPC policy is now relaxed to enable logging metrics for
+  // chrome URLs.
   ERR_IPC_FROM_BAD_URL_SCHEME,
 
   // If we track a navigation, but the renderer sends us no IPCs. This could
   // occur if the browser filters loads less aggressively than the renderer.
   ERR_NO_IPCS_RECEIVED,
 
   // Tracks frequency with which we record an abort time that occurred before
   // navigation start. This is expected to happen in some cases (see comments in
   // cc file for details). We use this error counter to understand how often it
   // happens.
@@ skipping 137 matching lines @@
   void UpdateAbortInternal(UserAbortType abort_type,
                            bool user_initiated,
                            base::TimeTicks timestamp,
                            bool is_certainly_browser_timestamp);
 
   // If |final_navigation| is null, then this is an "unparented" abort chain,
   // and represents a sequence of provisional aborts that never ends with a
   // committed load.
   void LogAbortChainHistograms(content::NavigationHandle* final_navigation);
 
+  void FilterObservers(content::NavigationHandle* navigation_handle);
+
   // Whether we stopped tracking this navigation after it was initiated. We may
   // stop tracking a navigation if it doesn't meet the criteria for tracking
   // metrics in DidFinishNavigation.
   bool did_stop_tracking_;
 
   // Whether the application went into the background when this PageLoadTracker
   // was active. This is a temporary boolean for UMA tracking.
   bool app_entered_background_;
 
   // The navigation start in TimeTicks, not the wall time reported by Blink.
@@ skipping 176 matching lines @@
 
   // Has the MWCO observed at least one navigation?
   bool has_navigated_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsWebContentsObserver);
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_METRICS_WEB_CONTENTS_OBSERVER_H_