Use CategoryFilter::kDefaultCategoryFilterString instead of "*" as the default category

build/android/adb_profile_chrome.py

Index: build/android/adb_profile_chrome.py
diff --git a/build/android/adb_profile_chrome.py b/build/android/adb_profile_chrome.py
index ba5b1ed554340a1c88aa46f925d0b38fd75732a5..a8b1eac5038cbfaf9ed21fc6e88c67fddb586314 100755
--- a/build/android/adb_profile_chrome.py
+++ b/build/android/adb_profile_chrome.py
@@ -34,7 +34,7 @@ def _GetSupportedBrowsers():
 
 def _StartTracing(adb, package_info, categories, continuous):
   adb.BroadcastIntent(package_info.package, 'GPU_PROFILER_START',
-                      '-e categories "%s"' % categories,
+                      '-e categories "%s"' % categories if categories else '',
                       '-e continuous' if continuous else '')
 
 
@@ -131,7 +131,7 @@ def _CaptureAndDownloadTimedTrace(adb, package_info, categories, interval,
 
 
 def _ComputeCategories(options):
-  categories = [options.categories]
+  categories = [options.categories] if options.categories else []
   if options.trace_cc:
     categories.append('disabled-by-default-cc.debug*')
   if options.trace_gpu:
@@ -163,7 +163,7 @@ def main():
   categories = optparse.OptionGroup(parser, 'Trace categories')
   categories.add_option('-c', '--categories', help='Select categories to trace '
                         'with comma-delimited wildcards, e.g., '
-                        '"*", "cat1*,-cat1a". Default is "*".', default='*')
+                        '"*", "cat1*,-cat1a".')

[Sami, 2013/10/14 11:22:19]

Having an emptry string imply default categories is a little problematic since
there's then no way to specify that you want no categories at all. Doing that
will be more useful after https://codereview.chromium.org/25686006/ when you
might only want to trace systrace categories.

How about we add a new constant, say, _DEFAULT_CHROME_CATEGORIES, that this
option will be set to by default. The _StartTracing then knows to avoid
specifying any categories in the intent if that constant is passed in.

[Xianzhu, 2013/10/14 16:44:40]

Do you mean '--categories ""' to opt-out chromium tracing? This seems
inconsistent with CategoryFilter which treats empty filter string as the default
categories. How about telling user here to pass "-*" for "no categories" (in
your patch)?

   categories.add_option('--trace-cc', help='Enable extra trace categories for '
                         'compositor frame viewer data.', action='store_true')
   categories.add_option('--trace-gpu', help='Enable extra trace categories for '