Override minimum logging level for breakpad to error messages.

Otherwise, minidump_stackwalk produces far more debug output than
actual output.

BUG=none
R=mark@chromium.org

Review URL: https://codereview.chromium.org/59163005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233242 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233242