[bisect] - Let perf try jobs specify revisions to test.

[bisect] - Let perf try jobs specify revisions to test.

Previously the perf try bots always used ToT and built with/without patch. This CL lets you specify a before/after revision instead, so that we can kick off perf try jobs with traces from the dashboard. Also did some refactoring to break up _RunPerformanceTest a bit.

BUG=433456
TEST=

Revisions Specified: http://build.chromium.org/p/tryserver.chromium.perf/builders/linux_perf_bisect/builds/1088
Existing: http://build.chromium.org/p/tryserver.chromium.perf/builders/linux_perf_bisect/builds/1087

Committed: https://crrev.com/88ed7eb5bc494aa90ebc92709c98e97abfa39821
Cr-Commit-Position: refs/heads/master@{#306427}

[shatch, 2014-12-01 21:05:35]

Patchset #1 (id:1) has been deleted

[shatch, 2014-12-01 21:05:41]

Patchset #1 (id:20001) has been deleted

[shatch, 2014-12-01 21:25:06]

Patchset #2 (id:60001) has been deleted

[shatch, 2014-12-01 22:29:26]

Patchset #1 (id:40001) has been deleted

[shatch, 2014-12-01 22:29:32]

Patchset #1 (id:80001) has been deleted

[shatch, 2014-12-01 22:29:38]

Patchset #1 (id:100001) has been deleted

[shatch, 2014-12-01 22:29:43]

Patchset #1 (id:120001) has been deleted

[shatch, 2014-12-01 22:29:49]

Patchset #1 (id:140001) has been deleted

[shatch, 2014-12-01 22:29:54]

Patchset #1 (id:80002) has been deleted

[shatch, 2014-12-02 17:07:34]

Patchset #1 (id:160001) has been deleted

[shatch, 2014-12-02 17:07:40]

Patchset #1 (id:170001) has been deleted

[shatch, 2014-12-02 17:07:46]

Patchset #1 (id:190001) has been deleted

[shatch, 2014-12-02 17:08:04]

Patchset #1 (id:200001) has been deleted

[shatch, 2014-12-02 17:08:13]

Patchset #1 (id:220001) has been deleted

[shatch, 2014-12-02 17:08:28]

Patchset #1 (id:240001) has been deleted

[shatch, 2014-12-02 17:11:56]

simonhatch@chromium.org changed reviewers:
+ prasadv@chromium.org

[prasadv, 2014-12-02 18:00:58]

lgtm

[shatch, 2014-12-02 18:22:27]

The CQ bit was checked by simonhatch@chromium.org

[commit-bot: I haz the power, 2014-12-02 18:24:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/740633006/260001

[commit-bot: I haz the power, 2014-12-02 19:01:32]

Committed patchset #1 (id:260001)

[commit-bot: I haz the power, 2014-12-02 19:02:12]

Patchset 1 (id:??) landed as
https://crrev.com/88ed7eb5bc494aa90ebc92709c98e97abfa39821
Cr-Commit-Position: refs/heads/master@{#306427}