Ignore unwanted perf data instead of raising exception.
Ignore unwanted perf data instead of raising exception.

TBR=cmp@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11448037

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@171415 0039d316-1c4b-4281-b951-d872f2087c98

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