autotest: graphics_Idle warn on busy CPU.

We often see failures due to active processes. Strictly speaking
the test can continue in these case. So just detect/warn about
this situation.

BUG=None.
TEST=None.

Change-Id: I402d786d7904e9fca984b7db42958f00729b9e7a
Reviewed-on: https://chromium-review.googlesource.com/231470
Commit-Queue: Ilja Friedel <ihf@chromium.org>
Tested-by: Ilja Friedel <ihf@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
1 file changed