Telemetry: add back browser flags for rendering

The flags were accidentally removed in crrev.com/c/1318395.

Bug: 903312
Change-Id: I89c20ceb807bb68ebb35f24bccf83fbc9482a117
Reviewed-on: https://chromium-review.googlesource.com/c/1329548
Commit-Queue: Ehsan Chiniforooshan <chiniforooshan@chromium.org>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#606905}

tools/perf/benchmarks/rendering.py

@@ -30,6 +30,10 @@ class RenderingDesktop(perf_benchmark.PerfBenchmark):
   def CreateStorySet(self, options):
     return page_sets.RenderingStorySet(platform='desktop')
 
+  def SetExtraBrowserOptions(self, options):
+    options.AppendExtraBrowserArgs('--enable-gpu-benchmarking')
+    options.AppendExtraBrowserArgs('--touch-events=enabled')
+
   def CreateCoreTimelineBasedMeasurementOptions(self):
     category_filter = chrome_trace_category_filter.CreateLowOverheadFilter()
     options = timeline_based_measurement.Options(category_filter)
@@ -58,6 +62,10 @@ class RenderingMobile(perf_benchmark.PerfBenchmark):
   def CreateStorySet(self, options):
     return page_sets.RenderingStorySet(platform='mobile')
 
+  def SetExtraBrowserOptions(self, options):
+    options.AppendExtraBrowserArgs('--enable-gpu-benchmarking')
+    options.AppendExtraBrowserArgs('--touch-events=enabled')
+
   def CreateCoreTimelineBasedMeasurementOptions(self):
     category_filter = chrome_trace_category_filter.CreateLowOverheadFilter()
     options = timeline_based_measurement.Options(category_filter)