GPUChannel pools mailbox names.

It asynchronously refills the pool to a target size when it falls below half that size.

GenerateMailboxNames is only synchronous if the pool is depleted. Common case is a few microseconds per name.

Review URL: https://chromiumcodereview.appspot.com/11362171

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166962 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed