Record histograms for timing information in DomDistiller.

tools/metrics/actions/actions.xml

 <!--
 Copyright 2014 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <!--
 This file is a comprehensive list of Chrome user actions along with the owner
 and description for each user action.
 
@@ skipping 2454 matching lines @@
   <owner>yfriedman@chromium.org</owner>
   <description>User opens a distilled page.</description>
 </action>
 
 <action name="DomDistiller_DistilledPagePrefsOpened">
   <owner>smaslo@chromium.org</owner>
   <owner>yfriedman@chromium.org</owner>
   <description>User opens distilled page preferences.</description>
 </action>
 
+<action name="DomDistiller_PageDistillable">
+  <owner>yfriedman@chromium.org</owner>
+  <description>
+    Records page loads for which using DomDistiller is possible.

[jwd, 2014/08/25 20:30:14]

Can these be caused without user action, such as an auto refreshing page?

Do you actually care about the extra timing information that user actions
provides? Or do you simply want a count? If it's just a count, then you can
achieve it using a UMA_HISTOGRAM_BOOLEAN histogram. This would give you better
dashboard support for filters and splitting by experiments, should you ever want
that.

[Yaron, 2014/08/25 20:41:32]

Currently, yes: https://chrome-internal-review.googlesource.com/#/c/173500/
Which extra timing info are you referring to?

[jwd, 2014/08/25 21:34:44]

Each user action that is recorded also records "when" it was recorded (it's not
an actual timestamp, but it lets you sequence data). This information is
currently only available through raw logs. 

Given that it's currently possible that this can be triggered by non user
actions, and since you weren't aware of the extra timing info, would it be
possible to change the implementation to use UMA_HISTOGRAM_BOOLEAN?

Like I said, we have much better dashboard support for it.

+  </description>
+</action>
+
+<action name="DomDistiller_PageNotDistillable">
+  <owner>yfriedman@chromium.org</owner>
+  <description>
+    Records page loads for which using DomDistiller is not possible.
+  </description>
+</action>
+
 <action name="Duplicate">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <description>Please enter the description of this user action.</description>
 </action>
 
 <action name="EasyUnlock_Enabled_Disable">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <description>Please enter the description of the metric.</description>
 </action>
 
@@ skipping 8999 matching lines @@
     apple-mobile-webapp-capable meta tag.
   </description>
 </action>
 
 <action name="webapps.AddShortcut.Bookmark">
   <owner>dfalcantara@chromium.org</owner>
   <description>Shortcut added to the homescreen for a bookmark.</description>
 </action>
 
 </actions>