Adjust the position of the menu of an action combobox

For an action combobox, remove the gap between the combobox
and menu, and have the menu aligned right.
This is the UX team's demand.

BUG=341793
TEST=manual

Review URL: https://codereview.chromium.org/159933009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250750 0039d316-1c4b-4281-b951-d872f2087c98
Add a pepper interface to histograms.xml.

This adds an enum entry for "PPB_ContentDecryptor_Private;0.10" to
PepperInterfaces, which I missed when I populated the initial set.

BUG=
R=asvitkine@chromium.org

Review URL: https://codereview.chromium.org/159113005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250751 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250751