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

chrome/browser/page_load_metrics/browser_page_track_decider.h

 // Copyright 2016 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_BROWSER_PAGE_TRACK_DECIDER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_BROWSER_PAGE_TRACK_DECIDER_H_
 
 #include "base/macros.h"
 #include "chrome/common/page_load_metrics/page_track_decider.h"
 
@@ skipping 10 matching lines @@
  public:
   // embedder_interface, web_contents, and navigation_handle are not owned by
   // BrowserPageTrackDecider, and must outlive the
   // BrowserPageTrackDecider.
   BrowserPageTrackDecider(PageLoadMetricsEmbedderInterface* embedder_interface,
                           content::WebContents* web_contents,
                           content::NavigationHandle* navigation_handle);
   ~BrowserPageTrackDecider() override;
 
   bool HasCommitted() override;
-  bool IsHttpOrHttpsUrl() override;
   bool IsNewTabPageUrl() override;
+  bool IsAboutBlankUrl() override;
   bool IsChromeErrorPage() override;
   bool IsHtmlOrXhtmlPage() override;
   int GetHttpStatusCode() override;
 
  private:
   PageLoadMetricsEmbedderInterface* const embedder_interface_;
   content::WebContents* const web_contents_;
   content::NavigationHandle* const navigation_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserPageTrackDecider);
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_BROWSER_PAGE_TRACK_DECIDER_H_