Fix refresh rate query for internal monitors

Fix refresh rate query for internal monitors

GetSelectedModeForDisplayId doesn't work for internal displays. This
results in failing the query, and falling back to refresh rate
approximation in the scheduler. To fix this, we use
GetActiveModeForDisplayId which exists even on internal displays.
This fixes the swap interval that the cc scheduler sees.

BUG=chromium:415359
TEST=make a trace on pixel, look at interval_us, it is a constant 16677 now (before it was variable and inaccurate)

Committed: https://crrev.com/1ad53a56f0872fe46103dcaa7f3a0199a825073e
Cr-Commit-Position: refs/heads/master@{#295505}

[marcheu, 2014-09-17 23:28:00]

marcheu@chromium.org changed reviewers:
+ oshima@chromium.org, piman@chromium.org

[oshima, 2014-09-18 05:12:34]

lgtm

[piman, 2014-09-18 17:40:45]

lgtm

[marcheu, 2014-09-18 17:42:24]

The CQ bit was checked by marcheu@chromium.org

[commit-bot: I haz the power, 2014-09-18 17:44:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/582543002/1

[commit-bot: I haz the power, 2014-09-18 18:44:46]

Committed patchset #1 (id:1) as 7f0a2e56a3e43c1fa8a95022223bb562793a891a

[commit-bot: I haz the power, 2014-09-18 18:45:42]

Patchset 1 (id:??) landed as
https://crrev.com/1ad53a56f0872fe46103dcaa7f3a0199a825073e
Cr-Commit-Position: refs/heads/master@{#295505}