Bring back chromium.perf.
Bring back chromium.perf.

Hardcoding a branch inside a revision with @ without reseting branch confuses
the Gclient step.

BUG=
TEST=


Review URL: http://codereview.chromium.org/8873045

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@113838 0039d316-1c4b-4281-b951-d872f2087c98

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