Add one extra UMA for video casting

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 e84d1dc4bd0c78219258ceae684e72f5b76e817d..7f1092e7e9bcdbb90601f95a54069903b916fd04 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -1343,6 +1343,10 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Cast.Sender.CastMediaType" enum="MediaContainers">
+  <summary>Records the media type of every video being cast.</summary>
+</histogram>
+
 <histogram name="Cast.Sender.CastPlaySuccess" enum="BooleanSuccess">
   <summary>
     Records the result of a request to play remotely. The value will be true if
@@ -27786,6 +27790,8 @@ other types of suffix sets.
   <int value="35" label="WAV / WAVE (Waveform Audio)"/>
   <int value="36" label="Matroska / WebM"/>
   <int value="37" label="WTV (Windows Television)"/>
+  <int value="38" label="DASH"/>

[Mark P, 2014/02/03 15:57:08]

Are these new values things that were previously counted, just counted as
value=0 UNKNOWN?

If so, standard good practices means that everytime you do this, you should
change the histogram name.  Otherwise the "Everything" view on the dashboard
will be mixing two different interpretations of the data and make no sense.

[Miguel Garcia, 2014/02/04 13:31:19]

Looking at the code they would have been categorized as UNKNOWN so I changed the
name of the metric. Thanks for spotting this.

On 2014/02/03 15:57:08, Mark P wrote:

+  <int value="39" label="SmoothStream"/>
 </enum>
 
 <enum name="MediaGalleriesUsageType" type="int">