[telemetry] Add new tracing benchmark for background mode memory-infra

tools/perf/benchmarks/tracing.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from core import perf_benchmark
 
+from telemetry import benchmark
+from telemetry.timeline import tracing_category_filter
+from telemetry.timeline import tracing_config
 from telemetry.web_perf import timeline_based_measurement
 
 import page_sets
 
 
 class TracingWithDebugOverhead(perf_benchmark.PerfBenchmark):
 
   page_set = page_sets.Top10PageSet
 
   def CreateTimelineBasedMeasurementOptions(self):
     options = timeline_based_measurement.Options(
         timeline_based_measurement.DEBUG_OVERHEAD_LEVEL)
     options.SetTimelineBasedMetric('tracingMetric')
     return options
 
   @classmethod
   def Name(cls):
     return 'tracing.tracing_with_debug_overhead'
+
+
+# Enable on reference builds once stable browser starts supporting background

[Zhen Wang, 2016/06/17 19:45:22]

Can you add it as TODO here?

[ssid, 2016/06/17 21:02:46]

Done.

+# mode memory-infra (after branch 2760).
+@benchmark.Disabled('reference')
+class TracingWithBackgroundMemoryInfra(perf_benchmark.PerfBenchmark):
+  """Measures the timeline metrics for overhead of background memory-infra

[Zhen Wang, 2016/06/17 19:45:22]

This should be one line. Then followed by detailed description if needed.

[ssid, 2016/06/17 21:02:46]

Done.

+  dumps"""
+  page_set = page_sets.Top10PageSet
+
+  def CreateTimelineBasedMeasurementOptions(self):
+    # Enable only memory-infra category with periodic background mode dumps
+    # every 200 milliseconds.
+    trace_memory = tracing_category_filter.TracingCategoryFilter(
+        filter_string='-*,blink.console,disabled-by-default-memory-infra')

[Zhen Wang, 2016/06/17 19:45:22]

What does "-*" mean here?

[ssid, 2016/06/17 21:02:46]

-* means it excludes all the default categories.
This is the same pattern followed here:
https://chromium.googlesource.com/chromium/src/+/master/tools/perf/benchmarks...

+    options = timeline_based_measurement.Options(overhead_level=trace_memory)
+    memory_dump_config = tracing_config.MemoryDumpConfig()
+    memory_dump_config.AddTrigger('background', 200)
+    options.config.SetMemoryDumpConfig(memory_dump_config)
+    options.SetTimelineBasedMetric('tracingMetric')
+    return options
+
+  @classmethod
+  def Name(cls):
+    return 'tracing.tracing_with_background_memory_infra'