Adds histograms for casting feature of Video Player

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 17f5530045f5c0f623bb8b8e905de23fa4f197b7..92c41d5c0b3c4dd9f84042e3345ed0c28ac1e946 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -39446,6 +39446,44 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="VideoPlayer.CastedVideoLength" units="seconds">
+  <owner>yoshiki@chromium.org</owner>
+  <summary>
+    Chrome OS Video Player: the length of casted video (in seconds).
+  </summary>
+</histogram>
+
+<histogram name="VideoPlayer.CastExtensionStatus"
+    enum="VideoPlayerCastExtensionStatus">
+  <owner>yoshiki@chromium.org</owner>
+  <summary>
+    Chrome OS Video Player: the statuses of the cast extension and the cast API
+    extension.

[Ilya Sherman, 2014/12/09 01:57:49]

Please document when this is recorded.

+  </summary>
+</histogram>
+
+<histogram name="VideoPlayer.NumberOfCastDevice">

[Ilya Sherman, 2014/12/09 01:57:49]

nit: typo: "Device" -> "Devices"

+  <owner>yoshiki@chromium.org</owner>
+  <summary>
+    Chrome OS Video Player: the number of cast devices. This value is recorded
+    after the cast extension finishes discovery.
+  </summary>
+</histogram>
+
+<histogram name="VideoPlayer.NumberOfOpenedFile">
+  <owner>yoshiki@chromium.org</owner>
+  <summary>
+    Chrome OS Video Player: the number of files being opened on launch.
+  </summary>
+</histogram>
+
+<histogram name="VideoPlayer.PlayType">

[Ilya Sherman, 2014/12/09 01:57:49]

Please associate an enum with this histogram (in this histograms.xml file).

+  <owner>yoshiki@chromium.org</owner>
+  <summary>
+    Chrome OS Video Player: type of playback (eg. local play, cast).
+  </summary>
+</histogram>
+
 <histogram name="Viewport.MetaTagType" enum="MetaTagTypeEnum">
   <owner>bokan@chromium.org</owner>
   <summary>
@@ -57013,6 +57051,16 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="7" label="YV12J"/>
 </enum>
 
+<enum name="VideoPlayerCastExtensionStatus" type="int">
+  <int value="0" label="Cast extension is unavailable."/>
+  <int value="1" label="Installation of Cast API extension is failed."/>
+  <int value="2" label="Load of Cast API extension is failed."/>
+  <int value="3"
+      label="Cast API extension is installed and loaded successfully."/>
+  <int value="4"
+      label="Cast API extension is available and loaded successfully."/>

[Ilya Sherman, 2014/12/09 01:57:49]

Optional: Long enum labels tend to be a little difficult to read, as they are
shown as labels in a table column.  I'd recommend shorter labels that omit
redundant information, e.g. "Unavailable", "Installation failed", "Load failed",
"Installed, loaded successfully", "Available, loaded successfully".

[Ilya Sherman, 2014/12/09 01:57:49]

Hmm, what is the difference between installed and available?

+</enum>
+
 <enum name="VideoRotation" type="int">
   <int value="0" label="VIDEO_ROTATION_0"/>
   <int value="1" label="VIDEO_ROTATION_90"/>