Fix build_dir configuration on tryserver.chromium.
Fix build_dir configuration on tryserver.chromium.

R=xusydoc@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/14224007

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@195105 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build