Add builders for tracing event's structural arguments

base/debug/trace_event_impl.h

 // Copyright (c) 2012 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.
 
 
 #ifndef BASE_DEBUG_TRACE_EVENT_IMPL_H_
 #define BASE_DEBUG_TRACE_EVENT_IMPL_H_
 
 #include <stack>
 #include <string>
@@ skipping 54 matching lines @@
 // For any argument of type TRACE_VALUE_TYPE_CONVERTABLE the provided
 // class must implement this interface.
 class ConvertableToTraceFormat : public RefCounted<ConvertableToTraceFormat> {
  public:
   // Append the class info to the provided |out| string. The appended
   // data must be a valid JSON object. Strings must be properly quoted, and
   // escaped. There is no processing applied to the content after it is
   // appended.
   virtual void AppendAsTraceFormat(std::string* out) const = 0;
 
+  std::string ToString() const {
+    std::string result;
+    AppendAsTraceFormat(&result);
+    return result;
+  }
+
  protected:
   virtual ~ConvertableToTraceFormat() {}
 
  private:
   friend class RefCounted<ConvertableToTraceFormat>;
 };
 
 struct TraceEventHandle {
   uint32 chunk_seq;
   uint16 chunk_index;
@@ skipping 652 matching lines @@
   scoped_refptr<MessageLoopProxy> flush_message_loop_proxy_;
   subtle::AtomicWord generation_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TRACE_EVENT_IMPL_H_