Change SecurityOrigin from ThreadSafeRefCounted to RefCounted
Change SecurityOrigin from ThreadSafeRefCounted to RefCounted

SecurityOrigin should be thread-local and therefore RefCounted.

BUG=415865

Review URL: https://codereview.chromium.org/665893002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@185270 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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