Allow system info to be attached when submitting a feedback report with performance data

R=xiyuan@chromium.org
BUG=309842

Review URL: https://codereview.chromium.org/51213011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232726 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232726