[tracing] Add filtering mode in TraceLog

base/trace_event/trace_config.h

Index: base/trace_event/trace_config.h
diff --git a/base/trace_event/trace_config.h b/base/trace_event/trace_config.h
index 87d0ae4109a983854e2542dc65e27816c4348b80..eba05738db1829e17ca2294a7758abdb6979e2b4 100644
--- a/base/trace_event/trace_config.h
+++ b/base/trace_event/trace_config.h
@@ -71,6 +71,8 @@ class BASE_EXPORT TraceConfig {
     // Reset the values in the config.
     void Clear();
 
+    void Merge(const MemoryDumpConfig& config);
+
     // Set of memory dump modes allowed for the tracing session. The explicitly
     // triggered dumps will be successful only if the dump mode is allowed in
     // the config.
@@ -240,6 +242,9 @@ class BASE_EXPORT TraceConfig {
   }
 
   const EventFilters& event_filters() const { return event_filters_; }
+  void SetEventFilterConfigs(const EventFilters& filter_configs) {

[oystein (OOO til 10th of July), 2016/10/13 00:34:30]

nit: SetEventFilters, for consistent naming (also 'Config' is somewhat redundant
in a config class).

[ssid, 2016/10/13 17:30:54]

SetEventFilters already exists in this class. Fixed it.

+    event_filters_ = filter_configs;
+  }
 
  private:
   FRIEND_TEST_ALL_PREFIXES(TraceConfigTest, TraceConfigFromValidLegacyFormat);