Add builders for tracing event's structural arguments

base/debug/trace_event_argument_unittest.cc

Index: base/debug/trace_event_argument_unittest.cc
diff --git a/base/debug/trace_event_argument_unittest.cc b/base/debug/trace_event_argument_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..768e62fd77d6edd17ee9fa31f904528fe83a9ec5
--- /dev/null
+++ b/base/debug/trace_event_argument_unittest.cc
@@ -0,0 +1,59 @@
+// Copyright (c) 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.
+
+#include "base/debug/trace_event_argument.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace debug {
+
+class TraceEventArgumentTest : public testing::Test {};
+
+TEST_F(TraceEventArgumentTest, FlatDitctionary) {
+  TracedValue value;
+  value.SetInteger("int", 2014)
+      .SetDouble("double", 0.0)
+      .SetBoolean("bool", true)
+      .SetString("string", "string");
+  scoped_refptr<base::debug::ConvertableToTraceFormat> convertable_value(
+      value.finish());
+  std::string json;
+  convertable_value->AppendAsTraceFormat(&json);
+  EXPECT_EQ("{\"bool\":true,\"double\":0.0,\"int\":2014,\"string\":\"string\"}",
+            json);
+}
+
+TEST_F(TraceEventArgumentTest, Hierarchy) {
+  TracedValue value;
+  value.SetInteger("i0", 2014)
+      .BeginDictionary("dict1")
+      .SetInteger("i1", 2014)

[alph, 2014/07/09 15:03:53]

Maybe use paddings to express the structure.

[yurys, 2014/07/09 15:04:54]

I would love to do so but 'git cl format' produced this output.

+      .BeginDictionary("dict2")
+      .SetBoolean("b2", false)
+      .EndDictionary()
+      .SetString("s1", "foo")
+      .EndDictionary()
+      .SetDouble("d0", 0.0)
+      .SetBoolean("b0", true)
+      .BeginArray("a1")
+      .PushInteger(1)
+      .PushBoolean(2)
+      .BeginDictionary()
+      .SetInteger("i2", 3)
+      .EndDictionary()
+      .EndArray()
+      .SetString("s0", "foo");
+  scoped_refptr<base::debug::ConvertableToTraceFormat> convertable_value(
+      value.finish());
+  std::string json;
+  convertable_value->AppendAsTraceFormat(&json);
+  EXPECT_EQ(
+      "{\"a1\":[1,true,{\"i2\":3}],\"b0\":true,\"d0\":0.0,\"dict1\":{\"dict2\":"
+      "{\"b2\":false},\"i1\":2014,\"s1\":\"foo\"},\"i0\":2014,\"s0\":"
+      "\"foo\"}",
+      json);
+}
+
+}  // namespace debug
+}  // namespace base