Add a command-line switch for bleeding-edge fast path Silk features.

BUG=

Review URL: https://codereview.chromium.org/168883003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252681 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252681
utils.expose: Make sure public interfaces are named

BUG=345429

Review URL: https://codereview.chromium.org/166873006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252682 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252682