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 5ef2c93c7e9cb479aeaa0c797a5a52499b1ec56d..579db9d79939b42103112dda2d973c6e47fea58e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -61243,6 +61243,14 @@ 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>
@@ -82829,6 +82837,15 @@ 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, with user gesture"/>
+  <int value="2" label="Same-origin subframe vibrate, no user gesture"/>
+  <int value="3" label="Same-origin subframe vibrate, with user gesture"/>
+  <int value="4" label="Cross-origin subframe vibrate, no user gesture"/>
+  <int value="5" label="Cross-origin subframe vibrate, with user gesture"/>
+</enum>
+
 <enum name="NetCacheState" type="int">
   <int value="0" label="FROM_CACHE"/>
   <int value="1" label="STILL_VALID"/>