Add /chrome/test/data/perf/third_party/ to .gitignore.

BUG=none
TBR=bulach@chromium.org

Review URL: https://codereview.chromium.org/11488023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@172238 0039d316-1c4b-4281-b951-d872f2087c98

.gitignore

@@ -94,6 +94,7 @@ v8.log
 /chrome/test/data/perf/frame_rate/content
 /chrome/test/data/perf/frame_rate/private
 /chrome/test/data/perf/private/
+/chrome/test/data/perf/third_party/
 /chrome/test/data/plugin/
 /chrome/test/data/pyauto_private
 /chrome/tools/memory