Fixed an issue where tracing events got incorrectly enabled.

base/trace_event/trace_config.cc

 // Copyright (c) 2015 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.
 
 #include "base/trace_event/trace_config.h"
 
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/strings/pattern.h"
 #include "base/strings/string_split.h"
@@ skipping 191 matching lines @@
          ++ci) {
       if (base::MatchPattern(category_group_token.c_str(), ci->c_str())) {
         // Current token of category_group_name is present in excluded_list.
         // Flag the exclusion and proceed further to check if any of the
         // remaining categories of category_group_name is not present in the
         // excluded_ list.
         category_group_disabled = true;
         break;
       }
       // One of the category of category_group_name is not present in
-      // excluded_ list. So, it has to be included_ list. Enable the
-      // category_group_name for recording.
-      category_group_disabled = false;
+      // excluded_ list. So, if it's not a disabled-by-default category,
+      // it has to be included_ list. Enable the category_group_name
+      // for recording.
+      if (!base::MatchPattern(category_group_token.c_str(),
+                              TRACE_DISABLED_BY_DEFAULT("*"))) {
+        category_group_disabled = false;
+      }
     }
     // One of the categories present in category_group_name is not present in
     // excluded_ list. Implies this category_group_name group can be enabled
     // for recording, since one of its groups is enabled for recording.
     if (!category_group_disabled)
       break;
   }
   // If the category group is not excluded, and there are no included patterns
   // we consider this category group enabled, as long as it had categories
   // other than disabled-by-default.
@@ skipping 429 matching lines @@
           str.at(0) == ' ' ||
           str.at(str.length() - 1) == ' ';
 }
 
 bool TraceConfig::HasIncludedPatterns() const {
   return !included_categories_.empty();
 }
 
 }  // namespace trace_event
 }  // namespace base