HiDPI images for ntp disclosure triangle, app promo button.

Also refresh the "n tabs recently closed" icon and add a 2x
version of the refreshed icon.

BUG=134372
TEST=visual
TBR=flackr

Review URL: https://chromiumcodereview.appspot.com/10701169

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@146545 0039d316-1c4b-4281-b951-d872f2087c98
4 files changed