Various cleaups for AMP page load metrics.

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 2caa87f1341aa824fcc9472852f4f4609995a460..13db7d35a84e696af554de2c7f642ef5c5db6175 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -89417,6 +89417,21 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
       name="PageLoad.ParseTiming.NavigationToParseStart.LoadType.ForwardBackNavigation"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PageLoadMetricsClientsAmp" separator="."
+    ordering="prefix">
+  <suffix name="Clients.AMP"
+      label="PageLoadMetrics that are a result of a navigations to an AMP
+             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="PageLoadMetricsClientsAmpCachePages" separator="."
     ordering="prefix">
   <obsolete>
@@ -89437,6 +89452,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram_suffixes name="PageLoadMetricsClientsAmpCachePages2" separator="."
     ordering="prefix">
+  <obsolete>
+    Deprecated in favor of PageLoad.Clients.AMP.*.
+  </obsolete>
   <suffix name="Clients.AMPCache2"
       label="PageLoadMetrics that are a result of a navigations to an AMP
              cache page. Same page navigations are not tracked."/>
@@ -89450,6 +89468,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="PageLoad.ParseTiming.NavigationToParseStart"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PageLoadMetricsClientsAmpType" separator=".">

[RyanSturm, 2017/05/15 20:42:06]

It might be cleaner to combine the two histogram_suffixes added in this CL,
since I expect they will always have the same list of affected-histograms.

[Bryan McQuade, 2017/05/16 03:59:15]

Done

+  <suffix name="AmpCache" label="AMP cache CDN"/>
+  <suffix name="GoogleSearch" label="Google Search AMP viewer"/>
+  <suffix name="GoogleNews" label="Google News AMP viewer"/>
+  <affected-histogram
+      name="PageLoad.Clients.AMP.DocumentTiming.NavigationToDOMContentLoadedEventFired"/>
+  <affected-histogram
+      name="PageLoad.Clients.AMP.DocumentTiming.NavigationToFirstLayout"/>
+  <affected-histogram
+      name="PageLoad.Clients.AMP.DocumentTiming.NavigationToLoadEventFired"/>
+  <affected-histogram
+      name="PageLoad.Clients.AMP.PaintTiming.NavigationToFirstContentfulPaint"/>
+  <affected-histogram
+      name="PageLoad.Clients.AMP.ParseTiming.NavigationToParseStart"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PageLoadMetricsClientsCssScanner" separator="."
     ordering="prefix">
   <suffix name="Clients.CssScanner"