Merge 75195 - Change the help center link on the sync setup encryption tab to...

Merge 75195 - Change the help center link on the sync setup encryption tab to point to the new article, depending on Chrome/ChromeOS platform.

BUG=72064
TEST=click "learn more" from encryption tab

Review URL: http://codereview.chromium.org/6525057

TBR=johnnyg@chromium.org
Review URL: http://codereview.chromium.org/6533014

git-svn-id: svn://svn.chromium.org/chrome/branches/648/src@75208 0039d316-1c4b-4281-b951-d872f2087c98