Add UMA metrics for "Cast..." menu item.

Add UMA metrics for "Cast..." menu item.

This change adds the following metrics:
- Time between the user opening the menu and clicking the "Cast..." item.
- Number of times the "Cast..." item is clicked.

BUG=593797
Committed: https://crrev.com/c96faa3bf8ca74c0173b8cfc88894c69063cf100
Cr-Commit-Position: refs/heads/master@{#380676}

[apacible, 2016-03-10 19:33:30]

Description was changed from

==========
asdf

BUG=
==========

to

==========
Add UMA metrics for "Cast..." menu item.

This change adds the following metrics:
- Time between the user opening the menu and clicking the "Cast..." item.
- Number of times the "Cast..." item is clicked.

BUG=593797
==========

[apacible, 2016-03-10 19:33:30]

apacible@chromium.org changed reviewers:
+ isherman@chromium.org, pkasting@chromium.org

[apacible, 2016-03-10 19:36:06]

PTAL, thanks!

[Ilya Sherman, 2016-03-10 23:43:20]

metrics lgtm

[Peter Kasting, 2016-03-11 00:38:30]

LGTM

[apacible, 2016-03-11 17:23:44]

The CQ bit was checked by apacible@chromium.org

[commit-bot: I haz the power, 2016-03-11 17:24:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1786453002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1786453002/1

[commit-bot: I haz the power, 2016-03-11 18:27:46]

Description was changed from

==========
Add UMA metrics for "Cast..." menu item.

This change adds the following metrics:
- Time between the user opening the menu and clicking the "Cast..." item.
- Number of times the "Cast..." item is clicked.

BUG=593797
==========

to

==========
Add UMA metrics for "Cast..." menu item.

This change adds the following metrics:
- Time between the user opening the menu and clicking the "Cast..." item.
- Number of times the "Cast..." item is clicked.

BUG=593797
==========

[commit-bot: I haz the power, 2016-03-11 18:27:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-11 18:29:06]

Description was changed from

==========
Add UMA metrics for "Cast..." menu item.

This change adds the following metrics:
- Time between the user opening the menu and clicking the "Cast..." item.
- Number of times the "Cast..." item is clicked.

BUG=593797
==========

to

==========
Add UMA metrics for "Cast..." menu item.

This change adds the following metrics:
- Time between the user opening the menu and clicking the "Cast..." item.
- Number of times the "Cast..." item is clicked.

BUG=593797

Committed: https://crrev.com/c96faa3bf8ca74c0173b8cfc88894c69063cf100
Cr-Commit-Position: refs/heads/master@{#380676}
==========

[commit-bot: I haz the power, 2016-03-11 18:29:07]

Patchset 1 (id:??) landed as
https://crrev.com/c96faa3bf8ca74c0173b8cfc88894c69063cf100
Cr-Commit-Position: refs/heads/master@{#380676}