Add UMAs 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 6a1961d47885f08227f44d481fd0415d107e8a0c..161606f16a24e214a1d65c88d12304473a9b288e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -1194,6 +1194,42 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Cast.Sender.CastButtonShown">

[Ilya Sherman, 2013/11/01 16:13:37]

Please associate an enum like "BooleanShown" with this histogram.

[Mark P, 2013/11/01 16:16:09]

perhaps:
units="Enabled"

ditto histogram below

[May, 2013/11/04 16:46:14]

Done.

+  <summary>
+    Records the number of times the cast button was shown to the user. The value
+    will be true if the button is enabled, and false if the button is disabled.
+    Note that depending on the current UX, it's possible that we hide the button
+    entirely if it's disabled, so it's possible for the false values to be 0.

[Mark P, 2013/11/01 16:16:09]

Wha?  This histogram is inappropriately named then.  Shouldn't it be called
something like
Cast.Sender.CastButtonEligibleToBeShown
?

analogous comment on histogram below

[May, 2013/11/04 16:46:14]

So currently, the Chromecast button shows up as an overlay when the user
fullscreens a video. This histogram is intended to record if the user can see
the button or not in that view. Given that the button is a regular Android
Button, it has the usual enabled/disabled state, which is something I wanted to
record also since obviously a user can't click on a disabled button. The current
UX (in beta, still subject to change) hides the button if it's not enabled,
hence the warning in the description that there might be no "disabled" values
recorded.


On 2013/11/01 16:16:09, Mark P wrote:

[Mark P, 2013/11/04 18:30:15]

Okay.  In this case, no change in the description and histogram name is
necessary.  (I would've preferred a better name in the first place, but this
name is not as far wrong as I originally thought.)

+  </summary>
+</histogram>
+
+<histogram name="Cast.Sender.CastButtonShownInitialFullscreen">

[Ilya Sherman, 2013/11/01 16:13:37]

Ditto.

[May, 2013/11/04 16:46:14]

Done.

+  <summary>
+    Records the number of times the cast button was shown to the user when the
+    video is fullscreened. The value will only be recorded once per fullscreen/
+    exit fullscreen session. The value will be true if the button is enabled,

[Mark P, 2013/11/01 16:16:09]

recorded on exit fullscreen then, I assume?
(also, if I close the browser when fullscreeen, I assume it might not be
incremented.)

[May, 2013/11/04 16:46:14]

No, recorded on enter fullscreen, but only once. So closing the browser while in
fullscreen would still be recorded.

On 2013/11/01 16:16:09, Mark P wrote:

+    and false if the button is disabled. Note that depending on the current UX,
+    it's possible that we hide the button entirely if it's disabled, so it's
+    possible for the false values to be 0.
+  </summary>
+</histogram>
+
+<histogram name="Cast.Sender.CastPlaySuccess">

[Ilya Sherman, 2013/11/01 16:13:37]

Please associate an enum with this histogram as well.

[Mark P, 2013/11/01 16:16:09]

perhaps:
units="Success"

[May, 2013/11/04 16:46:14]

Done.

+  <summary>
+    Records the result of a request to play remotely. The value will be true if
+    the playback succeeded, and false if there was an error.
+  </summary>
+</histogram>
+
+<histogram name="Cast.Sender.CastTimeRemainingPercentage"
+    units="percent remaining">
+  <summary>
+    Records the percentage of the video left by the time the remote playback is

[Mark P, 2013/11/01 16:16:09]

^by the^at the

Can you point me to where this histogram is emitted to?  I'd like to see what
the parameters (min, max, buckets, etc.) are for it.

[May, 2013/11/04 16:46:14]

I'll add you to the downstream change for this.

On 2013/11/01 16:16:09, Mark P wrote:

+    stopped. This will be recorded when the playback is stopped by the user, or
+    when it's stopped by the cast device.
+  </summary>
+</histogram>
+
 <histogram name="Cellular.ActivationFailure">
   <summary>
     The count of cellular device activation failures (Chrome OS).