[chromedriver] Quit Chrome before cleaning up temporary directories

[chromedriver] Quit Chrome before cleaning up temporary directories

BUG=
NOTRY=true
TBR=stgao@chromium.org

Committed: https://crrev.com/c76450400fcd81c0470e84010dcbd5215c6dc738
Cr-Commit-Position: refs/heads/master@{#300695}

[samuong, 2014-10-22 17:27:10]

The Windows builder is currently red because the Python tests are trying
deleting the user data directory before quitting Chrome. This is not good to do
on Linux or Mac either, but on Windows it will throw an error because some files
in the user data directory are still open.

http://build.chromium.org/p/chromium.chromedriver/builders/Win7/builds/6753

[samuong, 2014-10-22 17:27:13]

The CQ bit was checked by samuong@chromium.org

[samuong, 2014-10-22 17:28:16]

The CQ bit was unchecked by samuong@chromium.org

[samuong, 2014-10-22 17:31:19]

The CQ bit was checked by samuong@chromium.org

[commit-bot: I haz the power, 2014-10-22 17:32:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/671433005/20001

[commit-bot: I haz the power, 2014-10-22 17:35:18]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-10-22 17:36:19]

Patchset 2 (id:??) landed as
https://crrev.com/c76450400fcd81c0470e84010dcbd5215c6dc738
Cr-Commit-Position: refs/heads/master@{#300695}