Update ServiceWorker event handled status histogram

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 1990bc476b334c20e6e1b4683b9e2efad59d2cc6..acd35f1175c04473603c97eca6f27655cef3ede3 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -37283,6 +37283,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ServiceWorker.EventHandledStatus.Fetch"
+    enum="ServiceWorkerEventHandleStatus">
+  <owner>kinuko@chromium.org</owner>
+  <summary>
+    Records whether each fetch event is handled by ServiceWorker or not.
+  </summary>
+</histogram>
+
+<histogram name="ServiceWorker.EventHandledStatus.PerWorker.Fetch"
+    enum="ServiceWorkerPerWorkerEventHandleStatus">
+  <owner>kinuko@chromium.org</owner>
+  <summary>
+    Records how much of fetch events are handled compared with the number of
+    events that are fired for each ServiceWorker.  Recorded when each
+    ServiceWorkerVersion is destructed.
+  </summary>
+</histogram>
+
 <histogram name="ServiceWorker.FetchEvent.MainResource.Status"
     enum="ServiceWorkerStatusCode">
   <owner>falken@chromium.org</owner>
@@ -37502,6 +37520,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="ServiceWorker.UnhandledEventRatio" units="percent">
   <owner>kinuko@chromium.org</owner>
+  <obsolete>
+    Deprecated 2015-06 in favor of ServiceWorker.EventHandledStatus*.
+  </obsolete>
   <summary>
     Records the ratio of unhandled events to all events that are dispatched to
     each ServiceWorker.  Recorded when each ServiceWorkerVersion is destructed.
@@ -65853,6 +65874,17 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="2" label="MIGRATION_ERROR_FAILED"/>
 </enum>
 
+<enum name="ServiceWorkerEventHandleStatus" type="int">
+  <int value="0" label="EVENT_HANDLED"/>
+  <int value="1" label="EVENT_NOT_HANDLED"/>
+</enum>
+
+<enum name="ServiceWorkerPerWorkerEventHandleStatus" type="int">
+  <int value="0" label="ALL_EVENTS_HANDLED"/>
+  <int value="1" label="SOME_EVENTS_HANDLED"/>
+  <int value="2" label="NO_EVENTS_HANDLED"/>
+</enum>
+
 <enum name="ServiceWorkerReadResponseResult" type="int">
   <int value="0" label="OK"/>
   <int value="1" label="Read headers error"/>