cc: Remove task references from RasterWorkerPool.

This moves the responsibility to keep tasks alive while scheduled
from the RasterWorkerPool to the client where unnecessary reference
counting can be avoided. The result is a ~5x improvement in
BuildRasterTaskQueue performance, which under some circumstances
translate to almost 2x improvement in ScheduleTasks performance.

BUG=269841
TEST=cc_perftests --gtest_filter=RasterWorkerPool*

Review URL: https://codereview.chromium.org/173953003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253109 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253109
Enable webrtc for webview.

BUG=316499

Review URL: https://codereview.chromium.org/171463002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253110 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253110
use simple version of deepCopyTo -- easier to transition off of SkBitmap::Config

BUG=

Review URL: https://codereview.chromium.org/177433004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253111 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253111