Allow perf_id suffix to be added on runtime.
Allow perf_id suffix to be added on runtime.

I got some bots that need to graph the perf results by channel depending on the builds they get: win7-beta, win7-stable

Review URL: https://codereview.chromium.org/131353004

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@251086 0039d316-1c4b-4281-b951-d872f2087c98

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