Make the MockDRT implementation work again and add support for --actuals.

This fixes a bunch of issues that had broken over the months in the mock drt
code. Initial patch was from bungeman@chromium.org in
https://codereview.chromium.org/23889025/ . I've fixed the remaining issues
with the unit tests, fixed issues related to handling audio tests and virtual
test suites, and removed support for old test-shell style driver logic.

This code really shouldn't be called mock_drt at all, since drt doesn't
exist any more, either, but I'll save that for another day.

R=ojan@chromium.org, bungeman@chromium.org

Review URL: https://chromiumcodereview.appspot.com/23503087

git-svn-id: svn://svn.chromium.org/blink/trunk@158235 bbb929c8-8fbe-4397-9dbb-9b2b20218538
rmdir core/editing/chromium

There's no need to have a Chromium directory in editing. This CL just inlines
the one-line function into its one caller.

R=ojan

Review URL: https://chromiumcodereview.appspot.com/24363006

git-svn-id: svn://svn.chromium.org/blink/trunk@158236 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move away from SkImage::AlphaType to SkAlphaType.

This is a follow up to https://codereview.chromium.org/24130009/.

BUG=None
TEST=webkit_unit_tests --gtest_filter=Canvas2DLayerManagerTest.*
R=reed@google.com,senorblanco@chromium.org

Review URL: https://chromiumcodereview.appspot.com/24402002

git-svn-id: svn://svn.chromium.org/blink/trunk@158237 bbb929c8-8fbe-4397-9dbb-9b2b20218538