[PageLoadMetrics] Create page load timing metrics for H2/QUIC/H1 pages

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 9bc72edece9c6be84ef25f38314c7d1dc8443221..8d0ba2f660991d0aa68d6e2062e7f556de383f54 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -109329,6 +109329,27 @@ value.
   <affected-histogram name="PageLoad.ParseTiming.NavigationToParseStart"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PageLoadMetricsClientsProtocol" separator="."
+    ordering="prefix">
+  <suffix name="Clients.Protocol.H1"
+      label="PageLoadMetrics that are a result of a navigation to main
+             resource over HTTP/1.1"/>
+  <suffix name="Clients.Protocol.H2"
+      label="PageLoadMetrics that are a result of a navigation to main
+             resource over HTTP/2"/>
+  <suffix name="Clients.Protocol.QUIC"
+      label="PageLoadMetrics that are a result of a navigation to main
+             resource over QUIC"/>
+  <affected-histogram
+      name="PageLoad.DocumentTiming.NavigationToDOMContentLoadedEventFired"/>
+  <affected-histogram
+      name="PageLoad.DocumentTiming.NavigationToLoadEventFired"/>
+  <affected-histogram
+      name="PageLoad.Experimental.PaintTiming.ParseStartToFirstMeaningfulPaint"/>
+  <affected-histogram
+      name="PageLoad.PaintTiming.ParseStartToFirstContentfulPaint"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PageLoadMetricsClientsReload" separator="."
     ordering="prefix">
   <obsolete>