[Tracing] Add metadata filter

content/public/browser/tracing_controller.h

Index: content/public/browser/tracing_controller.h
diff --git a/content/public/browser/tracing_controller.h b/content/public/browser/tracing_controller.h
index 6467e95212fbb3a2c976274cf920154c81918773..f5bdd25c7dfd90af767542dc9aea223208fa7971 100644
--- a/content/public/browser/tracing_controller.h
+++ b/content/public/browser/tracing_controller.h
@@ -37,14 +37,17 @@ class TracingController {
   class CONTENT_EXPORT TraceDataSink
       : public base::RefCountedThreadSafe<TraceDataSink> {
    public:
+    TraceDataSink();
+
     virtual void AddTraceChunk(const std::string& chunk) {}
     virtual void SetSystemTrace(const std::string& data) {}
 
     // Notice that TracingController adds some default metadata when
-    // DisableRecording is called, which may override metadata that you would
+    // StopTracing is called, which may override metadata that you would
     // set beforehand in case of key collision.
     virtual void AddMetadata(const base::DictionaryValue& data);
-    virtual const base::DictionaryValue& GetMetadata() const;
+    virtual scoped_ptr<const base::DictionaryValue> GetMetadataCopy() const;
+    virtual void EnableMetadataFilter();
     // TODO(prabhur) Replace all the Set* functions with a generic function:
     // TraceDataSink::AppendAdditionalData(const std::string& name,
     // const std::string& trace_data)
@@ -56,6 +59,7 @@ class TracingController {
     virtual ~TraceDataSink() {}
 
    private:
+    bool requires_anonymized_metadata_;
     base::DictionaryValue metadata_;
   };