Add support for cellular geolocation

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 988cba66e31d5b6cc8570ad76b901902ab3f4564..b2eaa717b4de0afe9fc749d5232c44338bb239c2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -63208,6 +63208,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Events in reqests processing of IP-based SimpleGeolocation.</summary>
 </histogram>
 
+<histogram name="SimpleGeolocation.Request.HasCellTowers"
+    enum="SimpleGeolocationRequestHasCellTowers">
+  <owner>skylarc@chromium.org</owner>
+  <summary>
+    This boolean histogram counts SimpleGeolocationRequests carrying a nonzero
+    number of cell towers.
+  </summary>
+</histogram>
+
 <histogram name="SimpleGeolocation.Request.HasWiFiAccessPoints"
     enum="SimpleGeolocationRequestHasWiFiAccessPoints">
   <owner>alemate@chromium.org</owner>
@@ -105897,6 +105906,11 @@ value.
   <int value="4" label="Response malformed"/>
 </enum>
 
+<enum name="SimpleGeolocationRequestHasCellTowers" type="int">
+  <int value="0" label="No cell tower data in request."/>
+  <int value="1" label="Cell tower data present."/>
+</enum>
+
 <enum name="SimpleGeolocationRequestHasWiFiAccessPoints" type="int">
   <int value="0" label="No WiFi data in request."/>
   <int value="1" label="WiFi data present."/>