Remove trampoline between threads in SupportedImageTypeValidator.

Remove trampoline between threads in SupportedImageTypeValidator.

It's not necessary to trampoline between the IO thread and the blocking
worker pool. The actual image decoding takes place in another process
anyway; the task runner is merely used to invoke the callbacks.

BUG=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=205721

[vandebo (ex-Chrome), 2013-06-10 19:04:11]

LGTM

[commit-bot: I haz the power, 2013-06-10 19:04:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dcheng@chromium.org/16703003/1

[commit-bot: I haz the power, 2013-06-10 20:38:27]

Retried try job too often on chromium_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=chromium_p...

[dcheng, 2013-06-10 21:26:47]

+jhawkins for OWNERS approval.

[James Hawkins, 2013-06-11 00:00:18]

lgtm

[commit-bot: I haz the power, 2013-06-11 14:20:02]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dcheng@chromium.org/16703003/1

[commit-bot: I haz the power, 2013-06-11 18:29:46]

Retried try job too often on win_rel for step(s) sync_integration_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2013-06-11 23:20:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dcheng@chromium.org/16703003/1

[commit-bot: I haz the power, 2013-06-12 04:18:19]

Change committed as 205721