Fixing reporting of AMP page load information

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 b87b9ed851399d4defba65eaee2898c2d89f4fbb..eabc6983a25e139b7a157e86a99bfc7c21da22f2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -120119,6 +120119,9 @@ from previous Chrome versions.
 
 <histogram_suffixes name="PageLoadMetricsClientsAmpCachePages" separator="."
     ordering="prefix">
+  <obsolete>
+    Deprecated in favor of PageLoad.Clients.AMPCache2.*.
+  </obsolete>
   <suffix name="Clients.AMPCache"
       label="PageLoadMetrics that are a result of a navigations to an AMP
              cache page. Same page navigations are not tracked."/>
@@ -120132,6 +120135,21 @@ from previous Chrome versions.
   <affected-histogram name="PageLoad.ParseTiming.NavigationToParseStart"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PageLoadMetricsClientsAmpCachePages2" separator="."
+    ordering="prefix">
+  <suffix name="Clients.AMPCache2"
+      label="PageLoadMetrics that are a result of a navigations to an AMP
+             cache page. Same page navigations are not tracked."/>
+  <affected-histogram
+      name="PageLoad.DocumentTiming.NavigationToDOMContentLoadedEventFired"/>
+  <affected-histogram name="PageLoad.DocumentTiming.NavigationToFirstLayout"/>
+  <affected-histogram
+      name="PageLoad.DocumentTiming.NavigationToLoadEventFired"/>
+  <affected-histogram
+      name="PageLoad.PaintTiming.NavigationToFirstContentfulPaint"/>
+  <affected-histogram name="PageLoad.ParseTiming.NavigationToParseStart"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PageLoadMetricsClientsCssScanner" separator="."
     ordering="prefix">
   <suffix name="Clients.CssScanner"