64-bit support for Mac OS X in base_unittests.

BUG=44127, 18323
TEST=64-bit base_unittests should all pass
Review URL: http://codereview.chromium.org/2126001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@47275 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed