Add more metrics for VideoPersistence.

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 5e39c18450c4ece79ba0f4cf152aec9892a748fa..2bc778fa127620c9cf3738a82a739e111e46d4e3 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27658,6 +27658,37 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Pixel format used in HTML5 video. Emitted on video load.</summary>
 </histogram>
 
+<histogram name="Media.VideoPersistence.AttemptResult"
+    enum="VideoPersistenceAttemptResult">
+  <owner>mlamouri@chromium.org</owner>
+  <owner>peconn@chromium.org</owner>
+  <owner>zqzhang@chromium.org</owner>
+  <summary>
+    Every time a video persistence session could be triggered, it records the
+    result of the attempt.
+  </summary>
+</histogram>
+
+<histogram name="Media.VideoPersistence.Duration" units="ms">
+  <owner>mlamouri@chromium.org</owner>
+  <owner>peconn@chromium.org</owner>
+  <owner>zqzhang@chromium.org</owner>
+  <summary>
+    Records the length during which a video was in a persistent state. It is
+    recorded once per video persistence session.
+  </summary>
+</histogram>
+
+<histogram name="Media.VideoPersistence.EndReason"
+    enum="VideoPersistenceEndReason">
+  <owner>mlamouri@chromium.org</owner>
+  <owner>peconn@chromium.org</owner>
+  <owner>zqzhang@chromium.org</owner>
+  <summary>
+    Records the reason why a video persistence session has ended.
+  </summary>
+</histogram>
+
 <histogram name="Media.VideoPixelFormat" enum="VideoPixelFormat">
   <obsolete>
     Replaced by Media.VideoFormat 05/2015.
@@ -113155,6 +113186,27 @@ from previous Chrome versions.
   <int value="2" label="Landscape"/>
 </enum>
 
+<enum name="VideoPersistenceAttemptResult" type="int">
+  <int value="0" label="No system support"/>
+  <int value="1" label="No feature"/>
+  <int value="2" label="No activity support"/>
+  <int value="3" label="Already running"/>
+  <int value="4" label="Restarting"/>
+  <int value="5" label="Finishing"/>
+  <int value="6" label="No WebContents"/>
+  <int value="7" label="No video"/>
+  <int value="8" label="Success"/>

[Ilya Sherman, 2017/03/21 21:42:56]

nit: I'd suggest ordering "Success" to be first.  That way, if you ever add
additional error cases, it doesn't end up buried in the middle.

+</enum>
+
+<enum name="VideoPersistenceEndReason" type="int">
+  <int value="0" label="Resume"/>
+  <int value="1" label="Navigation"/>
+  <int value="2" label="Close"/>
+  <int value="3" label="Crash"/>
+  <int value="4" label="New tab"/>
+  <int value="5" label="Reparent"/>
+</enum>
+
 <enum name="VideoPixelFormat" type="int">
   <obsolete>
     Deprecated as of 05/2015. Substituted by VideoFormat.