Allow BlobDataHandles to be copied, and have their UUIDs read, on any thread.

BUG=108012

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=266817

Review URL: https://codereview.chromium.org/259773006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267423 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed