Cleanup: merge separate implementaions of ScreenshotDelegate for tests.

BUG=None
R=oshima@chromium.org
TEST=ash_unittests

Review URL: https://codereview.chromium.org/24257015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226118 0039d316-1c4b-4281-b951-d872f2087c98
Fix Effects PPAPI whitelist on Mac and Windows

BUG=297283

Review URL: https://codereview.chromium.org/24534004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226119 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226119