Replaces "nvpr mode" with "offscreen mode" and a flag to enable/
disable nvpr. Assigns new config names to the various combinations of
flags and begins printing them with the bench results in order to match
nanobench.
BUG=skia:
Review URL: https://codereview.chromium.org/1473253002
Repurposes the --nvpr flag as an int that says how many stencil samples
to use, or disables nvpr with a value of zero.
BUG=skia:
Review URL: https://codereview.chromium.org/1444543002
The newly created VisualLightweightBenchModule is just the old VisualBench.cpp, but gutted to only include timing code.
Future CLs will harden this abstraction, but for this CL the module owns a backpointer to VisualBench.cpp for a couple of calls.
BUG=skia:
Review URL: https://codereview.chromium.org/1304083007
