Add UMA to track permission changes from the content settings menu

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 6173e3de0485f977d8c524ef490082660b9e99c7..d09fe59690e3f98c145dbaf9a2c9b2e63c47b014 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -43404,13 +43404,52 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="WebsiteSettings.Menu.PermissionChanged" enum="ContentType">
+  <owner>miguelg@chromium.org</owner>
+  <owner>finnur@chromium.org</owner>
+  <summary>
+    Count of how often a specific content type (permission) is changed using the
+    content settings menu.
+  </summary>
+</histogram>
+
+<histogram name="WebsiteSettings.Menu.PermissionChanged.Allowed"
+    enum="ContentType">
+  <owner>miguelg@chromium.org</owner>
+  <owner>finnur@chromium.org</owner>
+  <summary>
+    Count of how often a specific content type (permission) is set to 'Allowed'
+    using the content settings menu.
+  </summary>
+</histogram>
+
+<histogram name="WebsiteSettings.Menu.PermissionChanged.Blocked"
+    enum="ContentType">
+  <owner>miguelg@chromium.org</owner>
+  <owner>finnur@chromium.org</owner>
+  <summary>
+    Count of how often a specific content type (permission) is set to 'Blocked'
+    using the content settings menu.
+  </summary>
+</histogram>
+
+<histogram name="WebsiteSettings.Menu.PermissionChanged.Reset"
+    enum="ContentType">
+  <owner>miguelg@chromium.org</owner>
+  <owner>finnur@chromium.org</owner>
+  <summary>
+    Count of how often a specific content type (permission) is reset to the
+    default value using the content settings menu.
+  </summary>
+</histogram>

[Ilya Sherman, 2015/02/23 22:55:20]

What sort of decisions are you planning to make based on these metrics?  You're
measuring how often users toggle states, but not measuring which states users
come to rest in.  Suppose that 100 people toggle back and forth between allowed
and blocked each  day, and all the remaining Chrome users toggle once, and then
come to rest where they land.  This metric will show you what the 100 people are
doing, but not what the Chrome population looks like.  Is that really what you
want to measure?

[Miguel Garcia, 2015/02/24 13:25:24]

The main motivation for this change is that we want to measure if there is any
significant change in the way people opt out of notifications after we launch
the push API. We want to do that by comparing how often the notification
permission notification changes compared to say geolocation. And how often it
changes over time as new web pages introduce the push API.


Also, together with the already existing Origin Info metrics below we'd like to
compare how often people toggle permissions from the omnibox padlock vs the
content settings menu.

On 2015/02/23 22:55:20, Ilya Sherman wrote:

+
 <histogram name="WebsiteSettings.OriginInfo.PermissionChanged"
     enum="ContentType">
   <owner>sashab@chromium.org</owner>
   <owner>felt@chromium.org</owner>
   <summary>
     Count of how often a specific content type (permission) is changed using the
-    Origin Info dialog on Android.
+    Origin Info dialog.
   </summary>
 </histogram>
 
@@ -43420,7 +43459,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <owner>felt@chromium.org</owner>
   <summary>
     Count of how often a specific content type (permission) is set to 'Allowed'
-    using the Origin Info dialog on Android.
+    using the Origin Info dialog.
   </summary>
 </histogram>
 
@@ -43430,7 +43469,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <owner>felt@chromium.org</owner>
   <summary>
     Count of how often a specific content type (permission) is set to 'Blocked'
-    using the Origin Info dialog on Android.
+    using the Origin Info dialog.
   </summary>
 </histogram>