tracing: simplify lifetime of TraceEventFilter(s)

base/trace_event/trace_log.h

Index: base/trace_event/trace_log.h
diff --git a/base/trace_event/trace_log.h b/base/trace_event/trace_log.h
index 88b6e588e406e70c064ebaea09918033354e15fc..d2048567a0781fa693347283d08eb69b1484f713 100644
--- a/base/trace_event/trace_log.h
+++ b/base/trace_event/trace_log.h
@@ -281,7 +281,8 @@ class BASE_EXPORT TraceLog : public MemoryDumpProvider {
 
   // Testing factory for TraceEventFilter.
   typedef std::unique_ptr<TraceEventFilter> (*FilterFactoryForTesting)(
-      const std::string& /* predicate_name */);
+      const std::string& /* predicate_name */,
+      std::unique_ptr<TraceEventFilter::Config>);
   void SetFilterFactoryForTesting(FilterFactoryForTesting factory) {
     filter_factory_for_testing_ = factory;
   }
@@ -355,14 +356,16 @@ class BASE_EXPORT TraceLog : public MemoryDumpProvider {
                     ProcessMemoryDump* pmd) override;
 
   // Enable/disable each category group based on the current mode_,
-  // category_filter_ and event_filters_enabled_.
-  // Enable the category group in the recording mode if category_filter_ matches
+  // category_filter_ and state of event filters.
+  void UpdateCategoryRegistry();
+
+  // Enable the category in the recording mode if trace config matches
   // the category group, is not null. Enable category for filtering if any
   // filter in event_filters_enabled_ enables it.
-  void UpdateCategoryRegistry();
   void UpdateCategoryState(TraceCategory* category);
 
-  void CreateFiltersForTraceConfig();
+  // Registers new TraceEventFilter(s) based on the current |trace_config_|.
+  void CreateFiltersAndUpdateFilterRegistry();
 
   // Configure synthetic delays based on the values set in the current
   // trace config.
@@ -473,7 +476,6 @@ class BASE_EXPORT TraceLog : public MemoryDumpProvider {
   subtle::AtomicWord /* Options */ trace_options_;
 
   TraceConfig trace_config_;
-  TraceConfig::EventFilters enabled_event_filters_;
 
   ThreadLocalPointer<ThreadLocalEventBuffer> thread_local_event_buffer_;
   ThreadLocalBoolean thread_blocks_message_loop_;