Increase trace buffer size for system_health.desktop_common

There's page sets that are flaky on Win7 GPU bots due to
the current 200mb buffer size being hit.

R=sullivan@chromium.org

Bug: 1046081
Change-Id: Ib2beacfaa68f5b5cb47065f72cbfd0ab23a1d46d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2023200
Auto-Submit: oysteine <oysteine@chromium.org>
Reviewed-by: Annie Sullivan <sullivan@chromium.org>
Commit-Queue: oysteine <oysteine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735610}

tools/perf/benchmarks/system_health.py

@@ -70,6 +70,12 @@ class DesktopCommonSystemHealth(_CommonSystemHealthBenchmark):
   def Name(cls):
     return 'system_health.common_desktop'
 
+  def CreateCoreTimelineBasedMeasurementOptions(self):
+    options = super(DesktopCommonSystemHealth,
+                    self).CreateCoreTimelineBasedMeasurementOptions()
+    options.config.chrome_trace_config.SetTraceBufferSizeInKb(300 * 1024)
+    return options
+
 
 @benchmark.Info(emails=['charliea@chromium.org', 'sullivan@chromium.org',
                         'tdresser@chromium.org',