CC: Fix overlow in multiply.

The soft limit calculation can overflow given high byte values.

BUG=345426

Review URL: https://codereview.chromium.org/175543002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252731 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252731