Change default on Mac to use_skia=1
Change default on Mac to use_skia=1

For context, see http://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/f8d4f43b6e66ab83#
Review URL: http://codereview.chromium.org/8002009

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@102532 0039d316-1c4b-4281-b951-d872f2087c98

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