cc: Checkerboarding in rendering benchmarks.

Add the checkerboarding metrics in the rendering benchmarks. Adding
these extra histograms do not affect the size of the output traces by
much. Below are some sample trace-sizes from pinpoint (10 traces for
each story):
 . On windows:
    - amazon_pinch: 56.32MB -> 56.32MB
    - twitter_pinch: 58.68MB -> 57.49MB
 . On pixel 2:
    - bouncing_balls_shadow: 41.69MB -> 41.74MB
    - bing_mobile: 57.08MB -> 57.14MB

BUG=984592

Change-Id: I3fdb065f8b85814a7b900c46b14f569ec406c243
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1785418Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694845}

tools/perf/benchmarks/rendering.py

@@ -36,6 +36,14 @@ class _RenderingBenchmark(perf_benchmark.PerfBenchmark):
         'Event.Latency.ScrollUpdate.Touch.TimeToScrollUpdateSwapBegin4',
         'Event.Latency.ScrollBegin.Wheel.TimeToScrollUpdateSwapBegin4',
         'Event.Latency.ScrollUpdate.Wheel.TimeToScrollUpdateSwapBegin4',
+        'Graphics.Smoothness.Checkerboarding.CompositorAnimation',
+        'Graphics.Smoothness.Checkerboarding.MainThreadAnimation',
+        'Graphics.Smoothness.Checkerboarding.PinchZoom',
+        'Graphics.Smoothness.Checkerboarding.RAF',
+        'Graphics.Smoothness.Checkerboarding.TouchScroll',
+        'Graphics.Smoothness.Checkerboarding.Video',
+        'Graphics.Smoothness.Checkerboarding.WheelScroll',
+        'Graphics.Smoothness.Throughput.MainThread.MainThreadAnimation',
         'Graphics.Smoothness.Throughput.MainThread.PinchZoom',
         'Graphics.Smoothness.Throughput.MainThread.RAF',
         'Graphics.Smoothness.Throughput.MainThread.TouchScroll',