[Android]: Hide add-to-homescreen app menu item when WebAPK is installed

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 1494ddb45114dca3faaf518ea1c3a89aa203d64f..84b567103e5fa0a775b5788e951a6bb82980ea1d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -754,6 +754,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Android.PrepareMenu.OpenWebApkVisibilityCheck" units="ms">

[pkotwicz, 2017/02/22 20:26:10]

Can you please update the histogram name?

[gonzalon, 2017/02/22 20:45:05]

I'm not sure I understand, this is the name you suggested, isn't it?

[pkotwicz, 2017/02/23 20:46:17]

Sorry. For some reason I thought that the histogram name differed from the name
passed to RecordHistogram.recordTimesHistogram() in Java code

+  <owner>hanxi@chromium.org</owner>
+  <owner>pkotwicz@chromium.org</owner>
+  <summary>
+    Measures the amount of time spent querying for a WebAPK name while preparing

[pkotwicz, 2017/02/22 20:26:10]

Nit: "querying for a WebAPK name" -> "querying for whether a WebAPK is already
installed"

[gonzalon, 2017/02/22 20:45:05]

Done.

+    the Chrome menu.
+  </summary>
+</histogram>
+
 <histogram name="Android.SeccompStatus.Prctl" enum="AndroidSeccompStatus">
   <owner>rsesek@chromium.org</owner>
   <summary>