Cleaned up the Cloud Print Preview No Destination Promotion.

- Fixed missing 2x closed button image
- Made it feel like a Chrome Native Overlay
- Changed the Cloud Print Learn More URL to "https"
- Removed the obsolete Cloud Print Image
- Focused by default the "Add a printer" buttton

Run chromium with --enable-print-preview to see the Cloud Print Preview UI.  To
simulate the No-Destinations promotion, I remove the "hidden" attribute in the
JS Console of #no-destinations-promo.

Before: http://i.imgur.com/z7UVEyZ.png
After:  http://i.imgur.com/fQknIFx.png

BUG=310610

Review URL: https://codereview.chromium.org/37393002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230514 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230514