Revert of Fix tab_switching measurement bug.

Revert of Fix tab_switching measurement bug. (patchset #9 id:160001 of https://codereview.chromium.org/1152763002/)

Reason for revert:
Looks like most of the perf tree has gone red with the tab_switching tests.

Original issue's description:
> Fix tab_switching measurement bug.
>
> _IsDone is always true, which makes it activate next tab regardless if the tab is rendered. It should wait until a reading of RWH_TabSwitchPaintDuration is obtained before switching to next tab. Also, it should pass each tab to GetHistogram(), not always the last tab. Unittest added. (./run_tests measurements.tab_switching).
>
> BUG=None
> CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:linux_perf_bisect;tryserver.chromium.perf:mac_perf_bisect;tryserver.chromium.perf:win_perf_bisect;tryserver.chromium.perf:android_nexus5_perf_bisect
>
> Committed: https://crrev.com/2eee3f91209b8ccf16e7f64c03d42fbafd724ebe
> Cr-Commit-Position: refs/heads/master@{#337191}

TBR=eakuefner@chromium.org,nednguyen@google.com,sullivan@chromium.org,deanliao@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None

Committed: https://crrev.com/3e221f683216ac851c0c91b85864fc90d1bf49c3
Cr-Commit-Position: refs/heads/master@{#337224}

[dsinclair, 2015-07-02 15:17:21]

Created Revert of Fix tab_switching measurement bug.

[commit-bot: I haz the power, 2015-07-02 15:18:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1212213003/1

[commit-bot: I haz the power, 2015-07-02 15:19:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-02 15:20:04]

Patchset 1 (id:??) landed as
https://crrev.com/3e221f683216ac851c0c91b85864fc90d1bf49c3
Cr-Commit-Position: refs/heads/master@{#337224}