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

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

 // 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.
 
 #include "chrome/browser/page_load_metrics/page_load_metrics_initialize.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
 #if defined(OS_ANDROID)
 #include "chrome/browser/page_load_metrics/observers/android_page_load_metrics_observer.h"
 #endif  // OS_ANDROID
 #include "chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/css_scanning_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/data_reduction_proxy_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/google_captcha_observer.h"
 #include "chrome/browser/page_load_metrics/observers/https_engagement_metrics/https_engagement_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/stale_while_revalidate_metrics_observer.h"
+#include "chrome/browser/page_load_metrics/observers/webui_page_load_metrics_observer.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search/search.h"
 #include "components/rappor/rappor_service.h"
 #include "content/public/browser/web_contents.h"
 #include "url/gurl.h"
 
 namespace chrome {
 
 namespace {
@@ skipping 46 matching lines @@
   tracker->AddObserver(base::WrapUnique(new CssScanningMetricsObserver()));
   std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
       no_state_prefetch_observer =
           NoStatePrefetchPageLoadMetricsObserver::CreateIfNeeded(web_contents_);
   if (no_state_prefetch_observer)
     tracker->AddObserver(std::move(no_state_prefetch_observer));
 #if defined(OS_ANDROID)
   tracker->AddObserver(
       base::MakeUnique<AndroidPageLoadMetricsObserver>(web_contents_));
 #endif  // OS_ANDROID
+  tracker->AddObserver(base::MakeUnique<WebUIPageLoadMetricsObserver>());
 }
 
 bool PageLoadMetricsEmbedder::IsPrerendering(
     content::WebContents* web_contents) {
   return prerender::PrerenderContents::FromWebContents(web_contents) != nullptr;
 }
 
 bool PageLoadMetricsEmbedder::IsNewTabPageUrl(const GURL& url) {
   Profile* profile =
       Profile::FromBrowserContext(web_contents_->GetBrowserContext());
   if (!profile)
     return false;
   return search::IsInstantNTPURL(url, profile);
 }
 
 }  // namespace
 
 void InitializePageLoadMetricsForWebContents(
     content::WebContents* web_contents) {
   page_load_metrics::MetricsWebContentsObserver::CreateForWebContents(
       web_contents, base::MakeUnique<PageLoadMetricsEmbedder>(web_contents));
 }
 
 }  // namespace chrome