Fixed an issue where tracing events got incorrectly enabled.

base/trace_event/trace_config_unittest.cc

 // Copyright 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/memory_dump_manager.h"
 #include "base/trace_event/trace_config.h"
 #include "base/trace_event/trace_config_memory_test_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ skipping 430 matching lines @@
   EXPECT_FALSE(tc.IsCategoryGroupEnabled("excluded"));
 
   // Enabled a disabled- category and also including makes all categories to
   // be traced require including.
   tc = TraceConfig("disabled-by-default-cc,included", "");
   EXPECT_STREQ("included,disabled-by-default-cc",
                tc.ToCategoryFilterString().c_str());
   EXPECT_TRUE(tc.IsCategoryGroupEnabled("disabled-by-default-cc"));
   EXPECT_TRUE(tc.IsCategoryGroupEnabled("included"));
   EXPECT_FALSE(tc.IsCategoryGroupEnabled("other_included"));
+
+  // Excluding categories won't enable disabled-by-default ones with the
+  // excluded category is also present in the group.
+  tc = TraceConfig("-excluded", "");
+  EXPECT_STREQ("-excluded", tc.ToCategoryFilterString().c_str());
+  EXPECT_FALSE(tc.IsCategoryGroupEnabled("excluded,disabled-by-default-cc"));
 }
 
 TEST(TraceConfigTest, IsEmptyOrContainsLeadingOrTrailingWhitespace) {
   // Test that IsEmptyOrContainsLeadingOrTrailingWhitespace actually catches
   // categories that are explicitly forbidden.
   // This method is called in a DCHECK to assert that we don't have these types
   // of strings as categories.
   EXPECT_TRUE(TraceConfig::IsEmptyOrContainsLeadingOrTrailingWhitespace(
       " bad_category "));
   EXPECT_TRUE(TraceConfig::IsEmptyOrContainsLeadingOrTrailingWhitespace(
@@ skipping 55 matching lines @@
 
 TEST(TraceConfigTest, LegacyStringToMemoryDumpConfig) {
   TraceConfig tc(MemoryDumpManager::kTraceCategory, "");
   EXPECT_TRUE(tc.IsCategoryGroupEnabled(MemoryDumpManager::kTraceCategory));
   EXPECT_NE(std::string::npos, tc.ToString().find("memory_dump_config"));
   EXPECT_EQ(2u, tc.memory_dump_config_.size());
 }
 
 }  // namespace trace_event
 }  // namespace base