Randomize order in which ready component updates are applied. On demand updates still take precedence.

BUG=343686

Review URL: https://codereview.chromium.org/144523004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255832 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255832