[polymer] Merge of master into polymer10-migration

telemetry/telemetry/timeline/chrome_trace_category_filter.py

Index: telemetry/telemetry/timeline/chrome_trace_category_filter.py
diff --git a/telemetry/telemetry/timeline/tracing_category_filter.py b/telemetry/telemetry/timeline/chrome_trace_category_filter.py
similarity index 83%
rename from telemetry/telemetry/timeline/tracing_category_filter.py
rename to telemetry/telemetry/timeline/chrome_trace_category_filter.py
index c417d13b57316f88d1697f5676b60a2962b2a644..203c5e95644cdf506eb81a33f346dcc451cecf3b 100644
--- a/telemetry/telemetry/timeline/tracing_category_filter.py
+++ b/telemetry/telemetry/timeline/chrome_trace_category_filter.py
@@ -5,7 +5,7 @@
 import re
 
 
-def CreateNoOverheadFilter():
+def CreateLowOverheadFilter():
   """Returns a filter with the least overhead possible.
 
   This contains no sub-traces of thread tasks, so it's only useful for
@@ -22,27 +22,45 @@ def CreateNoOverheadFilter():
     "blink.console",
     "trace_event_overhead"
   ]
-  return TracingCategoryFilter(filter_string=','.join(categories))
+  return ChromeTraceCategoryFilter(filter_string=','.join(categories))
 
 
-def CreateMinimalOverheadFilter():
-  """Returns a filter with the best-effort amount of overhead."""
-  return TracingCategoryFilter(filter_string='')
+def CreateDefaultOverheadFilter():
+  """Returns a filter with the best-effort amount of overhead.
+
+  This matches Chrome tracing's default category filter setting, i.e., enable
+  all categories except the disabled-by-default-* ones.
+
+  We should use '*' instead of '' (empty string) here. On the Chrome side, both
+  '*' and '' mean default category filter setting. However, if someone adds
+  additional category filters, the behavior becomes different.
+
+  For example:
+  '*': enable all categories except the disabled-by-default-* ones.
+  '':  enable all categories except the disabled-by-default-* ones.
+
+  Now add an additional category filter 'abc' to '*' and '':
+  '*,abc': enable all categories (including 'abc') except the
+           disabled-by-default-* ones.
+  'abc':   enable only 'abc', and disable all other ones.
+  """
+  return ChromeTraceCategoryFilter(filter_string='*')
 
 
 def CreateDebugOverheadFilter():
   """Returns a filter with as many traces enabled as is useful."""
-  return TracingCategoryFilter(filter_string='*,disabled-by-default-cc.debug')
+  return ChromeTraceCategoryFilter(
+      filter_string='*,disabled-by-default-cc.debug')
 
 
 _delay_re = re.compile(r'DELAY[(][A-Za-z0-9._;]+[)]')
 
 
-class TracingCategoryFilter(object):
+class ChromeTraceCategoryFilter(object):
   """A set of included and excluded categories that should be traced.
 
-  The TraceCategoryFilter allows fine tuning of what data is traced. Basic
-  choice of which tracers to use is done by TracingOptions.
+  The ChromeTraceCategoryFilter allows fine tuning of what data is traced for
+  Chrome. Basic choice of which tracers to use is done by TracingConfig.
 
   Providing filter_string=None gives the default category filter, which leaves
   what to trace up to the individual trace systems.