Workaround to make MemoryBarrier compile on Win x64

windows.h #defines "MemoryBarrier" on x64 (on x86 it's an forceinline function). Because atomicops.h uses MemoryBarrier as the public api name, workaround by #undefing and then calling the implementation directly.

ref: http://msdn.microsoft.com/en-us/library/windows/desktop/ms684208.aspx


R=brettw@chromium.org
BUG=166496

Review URL: https://chromiumcodereview.appspot.com/11888016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@176859 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed