[Prerender] first contentful paint histograms.

chrome/browser/prerender/prerender_histograms.h

Index: chrome/browser/prerender/prerender_histograms.h
diff --git a/chrome/browser/prerender/prerender_histograms.h b/chrome/browser/prerender/prerender_histograms.h
index 7fdc187567504a42fc24806be46898132a984016..ae66db172d175e62eddc5edbec5f8c236401e8db 100644
--- a/chrome/browser/prerender/prerender_histograms.h
+++ b/chrome/browser/prerender/prerender_histograms.h
@@ -52,6 +52,12 @@ class PrerenderHistograms {
                                    NavigationType navigation_type,
                                    const GURL& url);
 
+  // Record that a first contentful paint occured, and whether we were able to
+  // successfuly record the perceived FCP.
+  void RecordPerceivedFirstContentfulPaintStatus(Origin origin,
+                                                 bool successful,
+                                                 bool was_hidden);
+
   // Records, in a histogram, the percentage of the page load time that had
   // elapsed by the time it is swapped in.  Values outside of [0, 1.0] are
   // invalid and ignored.
@@ -121,26 +127,22 @@ class PrerenderHistograms {
                                    bool is_main_resource,
                                    int redirect_count) const;
 
-  // Records the time to first contentful paint.
-  // Must not be called for prefetch loads (which are never rendered anyway).
-  // |is_no_store| must be true if the main resource has a "no-store" cache
-  // control HTTP header.
-  // |prefetch_age| must be zero if the page was not prefetched.
-  void RecordFirstContentfulPaint(Origin origin,
-                                  bool is_no_store,
-                                  base::TimeDelta time,
-                                  base::TimeDelta prefetch_age);
-
-  // Returns the name of the histogram used to record the time to first
-  // contentful paint.
-  // Exposed for testing.
-  static std::string GetFirstContentfulPaintHistogramName(
-      Origin origin,
-      bool is_wash,
-      bool is_no_store,
-      base::TimeDelta prefetch_age);
+  // Records the time to first contentful paint with respect to a possible
+  // prefetch of the page. The time to first contentful paint with respect to
+  // the navigation start is recorded (even if the page was prererendered in
+  // advance of navigation start). One of several histograms is used, depending
+  // on whether this URL could have been prefetched before the navigation
+  // leading to the paint.
+  void RecordPrefetchFirstContentfulPaintTime(Origin origin,
+                                              bool is_no_store,
+                                              bool was_hidden,
+                                              base::TimeDelta time,
+                                              base::TimeDelta prefetch_age);
 
  private:
+  // The suffix used for first contentful paint visibility.
+  static std::string FirstContentfulPaintHiddenName(bool was_hidden);

[pasko, 2016/12/20 19:33:34]

this is not used outside prerender_histograms.cc, please move into the .cc and
anonymous namespace

[mattcary, 2016/12/21 17:08:58]

Done.

+
   base::TimeTicks GetCurrentTimeTicks() const;
 
   // Returns the time elapsed since the last prerender happened.