cc: Use const ref to avoid extra ref count of VideoProviderClientImpl.

cc: Use const ref to avoid extra ref count of VideoProviderClientImpl.

Use a const ref to avoid the expensive operation of incrementing the ref
count of RefCountedThreadSafe VideoProviderClientImpl.

BUG=336733
Committed: https://crrev.com/b9fe57c1d28a89abed11bf7e11dc7c03390e50af
Cr-Commit-Position: refs/heads/master@{#322633}

[sunnyps, 2015-03-27 18:58:02]

sunnyps@chromium.org changed reviewers:
+ danakj@chromium.org

[sunnyps, 2015-03-27 18:58:03]

PTAL.

[danakj, 2015-03-27 19:01:47]

Sure. LGTM

[sunnyps, 2015-03-27 19:02:10]

The CQ bit was checked by sunnyps@chromium.org

[commit-bot: I haz the power, 2015-03-27 19:03:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1039783002/1

[commit-bot: I haz the power, 2015-03-27 20:27:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-27 20:27:54]

Patchset 1 (id:??) landed as
https://crrev.com/b9fe57c1d28a89abed11bf7e11dc7c03390e50af
Cr-Commit-Position: refs/heads/master@{#322633}