Add a feature to display a persistence toggle for permission prompts on Android.

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 87938098d312bf886360bf03d6ebd92f53b04a74..4d6b932c5b31a37be1e9524c360ffbb65683ea04 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -39901,6 +39901,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Permissions.Prompt.Accepted.Persisted" enum="BooleanEnabled">

[Ilya Sherman, 2016/08/16 04:41:54]

Please provide an enum with custom labels for persist vs. don't persist (just
within this file -- no need to make C++ changes)

[dominickn, 2016/08/16 04:50:15]

Done.

+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    For each granted permission prompt displayed with a persistence toggle
+    (remember my decision), records whether the persistence toggle was enabled
+    (persist) or not enabled (don't persist).
+  </summary>
+</histogram>
+
 <histogram name="Permissions.Prompt.Denied" enum="PermissionRequestType">
   <owner>benwells@chromium.org</owner>
   <owner>tsergeant@chromium.org</owner>
@@ -39910,6 +39919,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Permissions.Prompt.Denied.Persisted" enum="BooleanEnabled">

[Ilya Sherman, 2016/08/16 04:41:54]

Ditto.

[dominickn, 2016/08/16 04:50:15]

Done.

+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    For each denied permission prompt displayed with a persistence toggle
+    (remember my decision), records whether the persistence toggle was enabled
+    (persist) or not enabled (don't persist).
+  </summary>
+</histogram>
+
 <histogram name="Permissions.Prompt.DismissCount">
   <owner>dominickn@chromium.org</owner>
   <summary>
@@ -101334,6 +101352,8 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="Permissions.Action"/>
   <affected-histogram name="Permissions.Action.InsecureOrigin"/>
   <affected-histogram name="Permissions.Action.SecureOrigin"/>
+  <affected-histogram name="Permissions.Prompt.Accepted.Persisted"/>
+  <affected-histogram name="Permissions.Prompt.Denied.Persisted"/>
   <affected-histogram name="Permissions.Prompt.DismissCount"/>
   <affected-histogram name="Permissions.Prompt.IgnoreCount"/>
   <affected-histogram name="Permissions.Requested.CrossOrigin"/>