[Prerender] first contentful paint histograms.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 31dc08efb3e571a645458f034bd7751ea9a40134..d0183f9dcfe3bd8348083e5ab1d868e50bba373e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -49325,6 +49325,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Prerender.PerceivedTTFCPRecorded" enum="BooleanEnabled">

[pasko, 2016/12/15 19:37:51]

please make another boolean

[mattcary, 2016/12/16 10:03:03]

Can you be more specific?

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

Oh, oops, that was indeed a bit cryptic.

This is BooleanEnabled, which is defined as:

<enum name="BooleanEnabled" type="int">
  <int value="0" label="Disabled"/>
  <int value="1" label="Enabled"/>
</enum>

I proposed another kind of boolean:

<enum name="BooleanRecorded" type="int">
  <int value="0" label="Not recorded"/>
  <int value="1" label="Recorded"/>
</enum>

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

Done.

+  <owner>droger@chromium.org</owner>
+  <owner>mattcary@chromium.org</owner>
+  <owner>pasko@chromium.org</owner>
+  <summary>
+    Whether perceived TTFCP was recorded successfully. If true, there is an
+    associated PrefetchTTFCP that records the TTFCP from the swapped-in
+    navigation start. If false, no PrefetchTTFCP was recorded.
+  </summary>
+</histogram>
+
 <histogram name="Prerender.PercentLoadDoneAtSwapin">
   <owner>pasko@chromium.org</owner>
   <summary>
@@ -49350,6 +49361,19 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Prerender.PrefetchTTFCP" units="ms">
+  <owner>droger@chromium.org</owner>
+  <owner>mattcary@chromium.org</owner>
+  <owner>pasko@chromium.org</owner>
+  <summary>
+    Time to first contentful paint (TTFCP) for navigations related to prefetch
+    (including prerender, no-state prefetch, and associated experiments). This
+    measures user-visible TTFCP. For no-state prefetch this is standard
+    navigation-to-FCP; for prerender this is the swapped-in prerender navigation

[pasko, 2016/12/15 19:37:51]

please explain what "swapped-in prerender navigation" means

[mattcary, 2016/12/16 10:03:03]

Done.

+    to FCP time.
+  </summary>
+</histogram>
+
 <histogram name="Prerender.PrerenderCountOf3Max">
   <owner>pasko@chromium.org</owner>
   <summary>
@@ -113118,6 +113142,7 @@ value.
              prefetched pages (bias)."/>
   <suffix name="Warm" label="Prefetch skips revalidation."/>
   <affected-histogram name="Prerender.NoStatePrefetchTTFCP"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="PrerenderPrefetchMainResourceType" separator=".">
@@ -113126,6 +113151,21 @@ value.
   <affected-histogram name="Prerender.NoStatePrefetchTTFCP.Cold"/>
   <affected-histogram name="Prerender.NoStatePrefetchTTFCP.Reference"/>
   <affected-histogram name="Prerender.NoStatePrefetchTTFCP.Warm"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Reference"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="PrerenderPrefetchPaintVisibility" separator=".">
+  <suffix name="Hidden" label="Page was hidden during rendering."/>
+  <suffix name="Visible" label="Page visible for all of rendering."/>
+  <affected-histogram name="Prerender.PerceivedTTFCPRecorded"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold.Cacheable"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold.NoStore"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Reference.Cacheable"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Reference.NoStore"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm.Cacheable"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm.NoStore"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="PrerenderSource" ordering="prefix">
@@ -113179,7 +113219,23 @@ value.
   <affected-histogram name="Prerender.PerceivedPLTMatchedComplete"/>
   <affected-histogram name="Prerender.PerceivedPLTWindowed"/>
   <affected-histogram name="Prerender.PerceivedPLTWindowNotMatched"/>
+  <affected-histogram name="Prerender.PerceivedTTFCPRecorded.Hidden"/>
+  <affected-histogram name="Prerender.PerceivedTTFCPRecorded.Visible"/>
   <affected-histogram name="Prerender.PercentLoadDoneAtSwapin"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold.Cacheable.Hidden"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold.Cacheable.Visible"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold.NoStore.Hidden"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Cold.NoStore.Visible"/>
+  <affected-histogram
+      name="Prerender.PrefetchTTFCP.Reference.Cacheable.Hidden"/>
+  <affected-histogram
+      name="Prerender.PrefetchTTFCP.Reference.Cacheable.Visible"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Reference.NoStore.Hidden"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Reference.NoStore.Visible"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm.Cacheable.Hidden"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm.Cacheable.Visible"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm.NoStore.Hidden"/>
+  <affected-histogram name="Prerender.PrefetchTTFCP.Warm.NoStore.Visible"/>
   <affected-histogram name="Prerender.PrerenderNotSwappedInPLT"/>
   <affected-histogram name="Prerender.PrerendersPerSessionCount"/>
   <affected-histogram name="Prerender.SimulatedLocalBrowsingBaselinePLT"/>