Always run Flush completion callbacks in Graphics2D.

Always run Flush completion callbacks in Graphics2D.

This fixes a leak because the completion callbacks were not getting run on
resource destruction. This leaves the calling code waiting for the callbacks
with leaked data associated with the callback.

This patch just always runs the callbacks with PP_ERROR_ABORTED. I tweaked the
callback code to use the (newer than the original code) "run and clear"
completion callback macro which also cleans up the code a little.

BUG=106402
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=113954

[yzshen1, 2011-12-05 22:09:47]

LGTM

Thanks!