GitLab

. Expose TableHeader::kHorizontalPadding so that it can be used in
  calculating preferred width of a column.
. Make TableHeader::OnMousePressed return false if not the left mouse
  button. This lets context menus on an ancestor work.
. Exposes couple of methods on TableView used by TaskManager.
. Fixes sizes in TableView.
. Turns on grouping in table example.

BUG=none
TEST=none
R=sadrul@chromium.org


Review URL: https://chromiumcodereview.appspot.com/11827007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175912 0039d316-1c4b-4281-b951-d872f2087c98