Measure the usage of navigator.vibrate in for user gesture & subframe.

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 68928e41b0bd17fea6c4f6287762d8517ac359c0..b39fd3b8012c97a87aeba66df56f728376782c81 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -60781,6 +60781,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Vibration.Context" enum="NavigatorVibrationType">
+  <owner>binlu@google.com</owner>
+  <summary>
+    Records instances of navigator.vibrate. Includes whether or not it comes
+    with a user gesture, same-origin subframe or cross-origin subframe.
+  </summary>
+</histogram>
+
 <histogram name="VideoPlayer.CastAPIExtensionStatus"
     enum="VideoPlayerCastAPIExtensionStatus">
   <owner>yoshiki@chromium.org</owner>
@@ -74785,8 +74793,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="847" label="DOMStringList_Item_AttributeGetter_Location"/>
   <int value="848" label="DOMStringList_Contains_Method_IndexedDB"/>
   <int value="849" label="DOMStringList_Contains_Method_Location"/>
-  <int value="850" label="NavigatorVibrate"/>
-  <int value="851" label="NavigatorVibrateSubFrame"/>
+  <int value="850" label="NavigatorVibrate (obsolete)"/>
+  <int value="851" label="NavigatorVibrateSubFrame (obsolete)"/>
   <int value="852" label="PermissionStatusStatus"/>
   <int value="853" label="V8XPathEvaluator_Constructor"/>
   <int value="854" label="V8XPathEvaluator_CreateExpression_Method"/>
@@ -82296,6 +82304,15 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="9" label="blob"/>
 </enum>
 
+<enum name="NavigatorVibrationType" type="int">
+  <int value="0" label="Main frame vibrate, no user gesture"/>
+  <int value="1" label="Main frame vibrate, user gesture"/>

[Michael van Ouwerkerk, 2016/06/28 11:45:53]

nit: "with user gesture" here and below, to contrast with "no user gesture"

+  <int value="2" label="Same-origin subframe vibrate, no user gesture"/>
+  <int value="3" label="Same-origin subframe vibrate, user gesture"/>
+  <int value="4" label="Cross-origin subframe vibrate, no user gesture"/>
+  <int value="5" label="Cross-origin subframe vibrate, user gesture"/>
+</enum>
+
 <enum name="NetCacheState" type="int">
   <int value="0" label="FROM_CACHE"/>
   <int value="1" label="STILL_VALID"/>