[Prerender] first contentful paint histograms.

chrome/browser/prerender/prerender_tab_helper.cc

Index: chrome/browser/prerender/prerender_tab_helper.cc
diff --git a/chrome/browser/prerender/prerender_tab_helper.cc b/chrome/browser/prerender/prerender_tab_helper.cc
index 096705dc8ab5c57a1f271d56271684e192e30a71..1aae2ea609343c5e18f3a7a7c6bb8c5bf4d76c70 100644
--- a/chrome/browser/prerender/prerender_tab_helper.cc
+++ b/chrome/browser/prerender/prerender_tab_helper.cc
@@ -26,16 +26,7 @@ PrerenderTabHelper::PrerenderTabHelper(content::WebContents* web_contents)
       origin_(ORIGIN_NONE),
       next_load_is_control_prerender_(false),
       next_load_origin_(ORIGIN_NONE),
-      weak_factory_(this) {
-  // Determine if this is a prerender.
-  PrerenderManager* prerender_manager = MaybeGetPrerenderManager();
-  if (prerender_manager &&
-      prerender_manager->IsWebContentsPrerendering(web_contents, &origin_)) {
-    navigation_type_ = NAVIGATION_TYPE_PRERENDERED;
-  } else {
-    navigation_type_ = NAVIGATION_TYPE_NORMAL;
-  }
-}
+      weak_factory_(this) {}
 
 PrerenderTabHelper::~PrerenderTabHelper() {
 }
@@ -106,12 +97,22 @@ void PrerenderTabHelper::DidStartProvisionalLoadForFrame(
     const GURL& validated_url,
     bool is_error_page,
     bool is_iframe_srcdoc) {
+  // Determine the navigation type.
+  PrerenderManager* prerender_manager = MaybeGetPrerenderManager();
+  if (prerender_manager &&
+      prerender_manager->IsWebContentsPrerendering(web_contents(), &origin_)) {
+    navigation_type_ = NAVIGATION_TYPE_PRERENDERED;
+  } else {
+    navigation_type_ = NAVIGATION_TYPE_NORMAL;
+  }
+
   if (render_frame_host->GetParent())
     return;
 
   // Record PPLT state for the beginning of a new navigation.
   pplt_load_start_ = GetTimeTicksFromPrerenderManager();
   actual_load_start_ = base::TimeTicks();
+  last_load_ = GetTimeTicksFromPrerenderManager();
 
   if (next_load_is_control_prerender_) {
     DCHECK_EQ(NAVIGATION_TYPE_NORMAL, navigation_type_);
@@ -156,10 +157,10 @@ void PrerenderTabHelper::PrerenderSwappedIn() {
   // Ensure we are not prerendering any more.
   DCHECK_EQ(NAVIGATION_TYPE_PRERENDERED, navigation_type_);
   DCHECK(!IsPrerendering());
+  last_swap_ = GetTimeTicksFromPrerenderManager();
   if (pplt_load_start_.is_null()) {
     // If we have already finished loading, report a 0 PPLT.
     RecordPerceivedPageLoadTime(base::TimeDelta(), 1.0);
-    DCHECK_EQ(NAVIGATION_TYPE_NORMAL, navigation_type_);
   } else {
     // If we have not finished loading yet, record the actual load start, and
     // rebase the start time to now.
@@ -173,6 +174,17 @@ void PrerenderTabHelper::WouldHavePrerenderedNextLoad(Origin origin) {
   next_load_origin_ = origin;
 }
 
+bool PrerenderTabHelper::LoadToPerceivedDelta(base::TimeDelta* delta) {
+  if (!last_load_.is_null() && !last_swap_.is_null() &&
+      last_swap_ >= last_load_) {
+    if (delta) {
+      *delta = last_swap_ - last_load_;
+    }
+    return true;
+  }
+  return false;
+}
+
 void PrerenderTabHelper::RecordPerceivedPageLoadTime(
     base::TimeDelta perceived_page_load_time,
     double fraction_plt_elapsed_at_swap_in) {
@@ -188,10 +200,6 @@ void PrerenderTabHelper::RecordPerceivedPageLoadTime(
   prerender_manager->RecordPerceivedPageLoadTime(
       origin_, navigation_type_, perceived_page_load_time,
       fraction_plt_elapsed_at_swap_in, url_);
-
-  // Reset state for the next navigation.
-  navigation_type_ = NAVIGATION_TYPE_NORMAL;
-  origin_ = ORIGIN_NONE;
 }
 
 }  // namespace prerender