Add WebPageImportanceSignals::issuedNonGetFetchFromScript()

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 97671a2a122d20d5d2ba37f4dffc25c238d9aea0..39defadcc859c90dd0489251a6f99d8d66c5e02e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -29696,6 +29696,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram
+    name="PageImportanceSignals.IssuedNonGetFetchFromScript.OnCommitLoad"
+    enum="IssuedNonGetFetchFromScript">
+  <owner>kouhei@chromium.org</owner>
+  <summary>
+    Number of pages that had issued non-GET fetch request from Javascript before
+    next page load.
+  </summary>
+</histogram>
+
 <histogram name="PageLoad.Timing.NavigationToDOMContentLoadedEventFired"
     units="milliseconds">
   <owner>bmcquade@chromium.org</owner>
@@ -62156,6 +62166,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="5" label="IPV6_INTERFACE_ARRAY_TOO_SHORT"/>
 </enum>
 
+<enum name="IssuedNonGetFetchFromScript" type="int">
+  <int value="0" label="No non-GET fetch request issued from script"/>
+  <int value="1" label="Observed non-GET fetch request issued from script"/>
+</enum>
+
 <enum name="JavaScriptAPIName" type="int">
   <int value="0" label="GetUserMedia"/>
   <int value="1" label="PeerConnection00"/>