Add builders for tracing event's structural arguments

base/debug/trace_event_argument.h

Index: base/debug/trace_event_argument.h
diff --git a/base/debug/trace_event_argument.h b/base/debug/trace_event_argument.h
new file mode 100644
index 0000000000000000000000000000000000000000..9d3535880b4e31847dcc8e30de8fde867c35628a
--- /dev/null
+++ b/base/debug/trace_event_argument.h
@@ -0,0 +1,59 @@
+// Copyright 2014 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_ARGUMENT_H_
+#define BASE_DEBUG_TRACE_EVENT_ARGUMENT_H_
+
+#include <string>
+#include <vector>
+
+#include "base/debug/trace_event.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+class DictionaryValue;
+class ListValue;
+class Value;
+
+namespace debug {
+
+class BASE_EXPORT TracedValue : public ConvertableToTraceFormat {
+ public:
+  TracedValue();
+
+  void EndDictionary();
+  void EndArray();
+
+  void SetInteger(const char* name, int value);
+  void SetDouble(const char* name, double);
+  void SetBoolean(const char* name, bool value);
+  void SetString(const char* name, const std::string& value);
+  void SetValue(const char* name, Value* value);
+  void BeginDictionary(const char* name);
+  void BeginArray(const char* name);
+
+  void AppendInteger(int);
+  void AppendDouble(double);
+  void AppendBoolean(bool);
+  void AppendString(const std::string&);
+  void BeginArray();
+  void BeginDictionary();
+
+  virtual void AppendAsTraceFormat(std::string* out) const OVERRIDE;
+
+ private:
+  virtual ~TracedValue();
+
+  DictionaryValue* GetCurrentDictionary();
+  ListValue* GetCurrentArray();
+
+  scoped_ptr<base::Value> root_;
+  std::vector<Value*> stack_;
+  DISALLOW_COPY_AND_ASSIGN(TracedValue);
+};
+
+}  // namespace debug
+}  // namespace base
+
+#endif  // BASE_DEBUG_TRACE_EVENT_ARGUMENT_H_