Fix PPLT metric for the new TabContents based prerendering

chrome/browser/prerender/prerender_manager.cc

 // Copyright (c) 2011 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/prerender/prerender_manager.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/favicon/favicon_tab_helper.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/prerender/prerender_final_status.h"
+#include "chrome/browser/prerender/prerender_observer.h"
 #include "chrome/browser/prerender/prerender_tracker.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper_delegate.h"
 #include "chrome/common/render_messages.h"
 #include "content/browser/browser_thread.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/renderer_host/render_process_host.h"
 #include "content/browser/renderer_host/resource_dispatcher_host.h"
 #include "content/browser/tab_contents/render_view_host_manager.h"
@@ skipping 574 matching lines @@
 
   GURL icon_url = prerender_contents->icon_url();
   if (!icon_url.is_empty()) {
     std::vector<FaviconURL> urls;
     urls.push_back(FaviconURL(icon_url, FaviconURL::FAVICON));
     new_tab_contents->favicon_tab_helper()->OnUpdateFaviconURL(
         prerender_contents->page_id(),
         urls);
   }
 
+  // Update PPLT metrics:
+  // If the tab has finished loading, record a PPLT of 0.
+  // If the tab is still loading, reset its start time to the current time.
+  PrerenderObserver* prerender_observer =
+      new_tab_contents->prerender_observer();
+  DCHECK(prerender_observer != NULL);
+  prerender_observer->PrerenderSwappedIn();
+
   // See if we have any pending prerender requests for this routing id and start
   // the preload if we do.
   std::pair<int, int> child_route_pair = std::make_pair(child_id, route_id);
   PendingPrerenderList::iterator pending_it =
       pending_prerender_list_.find(child_route_pair);
   if (pending_it != pending_prerender_list_.end()) {
     for (std::vector<PendingContentsData>::iterator content_it =
             pending_it->second.begin();
          content_it != pending_it->second.end(); ++content_it) {
       AddPreload(pending_it->first, content_it->url_, content_it->referrer_);
@@ skipping 379 matching lines @@
   base::TimeTicks cutoff = GetCurrentTimeTicks() -
       base::TimeDelta::FromMilliseconds(kNavigationRecordWindowMs);
   while (!navigations_.empty()) {
     if (navigations_.front().time_ > cutoff)
       break;
     navigations_.pop_front();
   }
 }
 
 }  // namespace prerender