Allow perf_id to be used without a mapping.
Allow perf_id to be used without a mapping.

BUG=79801

Review URL: http://codereview.chromium.org/6877016

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@82015 0039d316-1c4b-4281-b951-d872f2087c98

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