Trace category groups and category filter.

base/debug/trace_event_impl.h

Index: base/debug/trace_event_impl.h
diff --git a/base/debug/trace_event_impl.h b/base/debug/trace_event_impl.h
index fb9c5791021ed3b26ef34142f74264a45dc024a4..3c25f2ac33b276238a44225db48f5c5b960a1f3f 100644
--- a/base/debug/trace_event_impl.h
+++ b/base/debug/trace_event_impl.h
@@ -176,26 +176,30 @@ class BASE_EXPORT TraceLog {
   // The known categories are inserted into |categories|.
   void GetKnownCategories(std::vector<std::string>* categories);
 
-  // Enable tracing for provided list of categories. If tracing is already
-  // enabled, this method does nothing -- changing categories during trace is
-  // not supported.
-  // If both included_categories and excluded_categories are empty,
-  //   all categories are traced.
-  // Else if included_categories is non-empty, only those are traced.
-  // Else if excluded_categories is non-empty, everything but those are traced.
+  // Enable tracing for provided list of category tags. If tracing is already
+  // enabled, this method does nothing -- changing category tags during trace
+  // is not supported.
+  // If both included_tag_patterns and excluded_tag_patterns are empty,
+  // all categories are traced.
+  // Else if included_tag_patterns is non-empty, only those categories with
+  // matching tags are traced.
+  // Else if excluded_tag_patterns is non-empty, everything but those
+  // categories with matching tags are traced.
   // Wildcards * and ? are supported (see MatchPattern in string_util.h).
-  void SetEnabled(const std::vector<std::string>& included_categories,
-                  const std::vector<std::string>& excluded_categories);
+  void SetEnabled(const std::vector<std::string>& included_tag_patterns,
+                  const std::vector<std::string>& excluded_tag_patterns);
 
-  // |categories| is a comma-delimited list of category wildcards.
-  // A category can have an optional '-' prefix to make it an excluded category.
+  // |tag_patterns| is a comma-delimited list of category tag wildcards.
+  // A tag pattern can have an optional '-' prefix to exclude categories
+  // with matching tags excluded.
+  //
   // All the same rules apply above, so for example, having both included and
-  // excluded categories in the same list would not be supported.
+  // excluded category tags in the same list would not be supported.
   //
   // Example: SetEnabled("test_MyTest*");
   // Example: SetEnabled("test_MyTest*,test_OtherStuff");
-  // Example: SetEnabled("-excluded_category1,-excluded_category2");
-  void SetEnabled(const std::string& categories);
+  // Example: SetEnabled("-excluded_category_tag1,-excluded_category_tag2");
+  void SetEnabled(const std::string& tag_patterns);
 
   // Retieves the categories set via a prior call to SetEnabled(). Only
   // meaningful if |IsEnabled()| is true.
@@ -250,6 +254,8 @@ class BASE_EXPORT TraceLog {
   void Flush(const OutputCallback& cb);
 
   // Called by TRACE_EVENT* macros, don't call this directly.
+  // The name parameter is a category name that can be made up of tags, for
+  // example: TRACE_EVENT0("renderer,webkit", "WebViewImpl::HandleInputEvent")
   static const unsigned char* GetCategoryEnabled(const char* name);
   static const char* GetCategoryName(const unsigned char* category_enabled);
 
@@ -370,8 +376,8 @@ class BASE_EXPORT TraceLog {
   int enable_count_;
   NotificationCallback notification_callback_;
   std::vector<TraceEvent> logged_events_;
-  std::vector<std::string> included_categories_;
-  std::vector<std::string> excluded_categories_;
+  std::vector<std::string> included_tag_patterns_;
+  std::vector<std::string> excluded_tag_patterns_;
   bool dispatching_to_observer_list_;
   ObserverList<EnabledStateChangedObserver> enabled_state_observer_list_;