Reland of Pass --images '' to nanobench to disable image benchmarking. (patchset #1 id:1 of https://codereview.chromium.org/1400633002/ )

Reason for revert:
Still breaking. e.g.

http://build.chromium.org/p/client.skia/builders/Test-iOS-Clang-iPad4-GPU-SGX554-Arm7-Debug/builds/1466/steps/nanobench/logs/stdio

http://build.chromium.org/p/client.skia.android/builders/Perf-Android-GCC-Nexus7-GPU-Tegra3-Arm7-Release/builds/2280/steps/nanobench/logs/stdio

Original issue's description:
> Revert of Pass --images '' to nanobench to disable image benchmarking. (patchset #1 id:1 of https://codereview.chromium.org/1381703003/ )
>
> Reason for revert:
> I have attempted to fix the problems that caused running nanobench with images to fail, so testing to see if they are in fact fixed.
>
> Original issue's description:
> > Pass --images '' to nanobench to disable image benchmarking.
> >
> > Enabling image benchmarking has caused most nanobench runs to fail,
> > both Debug and Release.
> >
> > BUG=skia:3418
> > NOTREECHECKS=true
> > TBR=scroggo@google.com
> >
> > Committed: https://skia.googlesource.com/skia/+/1f7039c6c5f0f118b629994b0bac255345e5abd6
>
> BUG=skia:3418
>
> Committed: https://skia.googlesource.com/skia/+/c2e59caa0a466040f4b4f08cb5604c86b2615efa

TBR=mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:3418

Review URL: https://codereview.chromium.org/1396843003
2 files changed