Implemented printToSkPicture without using WebViewBenchmarkSupport.
The new implementation grabs the compositor layer-tree and
recursively paints each layer into an SkPicture. Nothing should
change functionally. It is just moving the implementation from
WebKit side to Chrome side.
Once this patch lands, WebViewBenchmarkSupport can be deleted.
BUG=168460
Review URL: https://chromiumcodereview.appspot.com/
23049007
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@218611 0039d316-1c4b-4281-b951-d872f2087c98