cc: Avoid issuing COMMANDS_COMPLETED queries unless necessary.

Minor change to the Fence API that allows GLRenderer to not
issue sync queries unless some resource that depend on them
was used to produce a frame.

Also includes some minor renaming cleanup related to usage of
Fences in ResourceProvider code.

Change-Id: I45165a8f6a91b3ad56c5db02489ea83a782d6b05
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284318