Force software rasterization on ThreadTimesCompositorCases benchmark.

tools/perf/benchmarks/thread_times.py

Index: tools/perf/benchmarks/thread_times.py
diff --git a/tools/perf/benchmarks/thread_times.py b/tools/perf/benchmarks/thread_times.py
index 055f1fbd6d020aeec760326fb8db3083656b0b38..6cad6bc92d8d475f3fe03aef1664a590e7b4990f 100644
--- a/tools/perf/benchmarks/thread_times.py
+++ b/tools/perf/benchmarks/thread_times.py
@@ -52,11 +52,13 @@ class ThreadTimesSimpleMobileSites(benchmark.Benchmark):
 
 class ThreadTimesCompositorCases(benchmark.Benchmark):
   """Measures timeline metrics while performing smoothness action on
-  tough compositor cases.
+  tough compositor cases, using software rasterization.
+
   http://www.chromium.org/developers/design-documents/rendering-benchmarks"""
   test = thread_times.ThreadTimes
   page_set = page_sets.ToughCompositorCasesPageSet
-
+  def CustomizeBrowserOptions(self, options):
+    silk_flags.CustomizeBrowserOptionsForSoftwareRasterization(options)
 
 @benchmark.Enabled('android')
 class ThreadTimesPolymer(benchmark.Benchmark):