Make UserManager::TPMTokenInfoDelegate::GetTokenInfo thread safe.
Make UserManager::TPMTokenInfoDelegate::GetTokenInfo thread safe.

Change-Id: I251481f0feb3f782f34213b5dc731847b7e42ae9

BUG=chromium-os:24836
TEST=Ensure login times are not any slower and that UI for connecting to a network with a certificate works and does not stall. Also ensure crash in issue stops showing up.


Review URL: http://codereview.chromium.org/9323048

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@120461 0039d316-1c4b-4281-b951-d872f2087c98

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