[tracing] Optimize TracedValue::AppendAsTraceFormat().

base/trace_event/trace_event_argument_unittest.cc

 // 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/trace_event/trace_event_argument.h"
 
 #include <stddef.h>
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "base/values.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 namespace trace_event {
 
 TEST(TraceEventArgumentTest, FlatDictionary) {
   std::unique_ptr<TracedValue> value(new TracedValue());
+  value->SetBoolean("bool", true);
+  value->SetDouble("double", 0.0);
   value->SetInteger("int", 2014);
-  value->SetDouble("double", 0.0);
-  value->SetBoolean("bool", true);
   value->SetString("string", "string");
   std::string json = "PREFIX";
   value->AppendAsTraceFormat(&json);
   EXPECT_EQ(
       "PREFIX{\"bool\":true,\"double\":0.0,\"int\":2014,\"string\":\"string\"}",
       json);
 }
 
 TEST(TraceEventArgumentTest, NoDotPathExpansion) {
   std::unique_ptr<TracedValue> value(new TracedValue());
+  value->SetBoolean("bo.ol", true);
+  value->SetDouble("doub.le", 0.0);
   value->SetInteger("in.t", 2014);
-  value->SetDouble("doub.le", 0.0);
-  value->SetBoolean("bo.ol", true);
   value->SetString("str.ing", "str.ing");
   std::string json;
   value->AppendAsTraceFormat(&json);
   EXPECT_EQ(
       "{\"bo.ol\":true,\"doub.le\":0.0,\"in.t\":2014,\"str.ing\":\"str.ing\"}",
       json);
 }
 
 TEST(TraceEventArgumentTest, Hierarchy) {
   std::unique_ptr<TracedValue> value(new TracedValue());
-  value->SetInteger("i0", 2014);
-  value->BeginDictionary("dict1");
-  value->SetInteger("i1", 2014);
-  value->BeginDictionary("dict2");
-  value->SetBoolean("b2", false);
-  value->EndDictionary();
-  value->SetString("s1", "foo");
-  value->EndDictionary();
-  value->SetDouble("d0", 0.0);
-  value->SetBoolean("b0", true);
   value->BeginArray("a1");
   value->AppendInteger(1);
   value->AppendBoolean(true);
   value->BeginDictionary();
   value->SetInteger("i2", 3);
   value->EndDictionary();
   value->EndArray();
+  value->SetBoolean("b0", true);
+  value->SetDouble("d0", 0.0);
+  value->BeginDictionary("dict1");
+  value->BeginDictionary("dict2");
+  value->SetBoolean("b2", false);
+  value->EndDictionary();
+  value->SetInteger("i1", 2014);
+  value->SetString("s1", "foo");
+  value->EndDictionary();
+  value->SetInteger("i0", 2014);
   value->SetString("s0", "foo");
   std::string json;
   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);
 }
 
@@ skipping 83 matching lines @@
   nested_dict_value->SetInteger("f", 3);
   nested_dict_value->BeginDictionary("g");
   nested_dict_value->EndDictionary();
   json = "";
   nested_dict_value->AppendAsTraceFormat(&json);
   EXPECT_EQ("{\"b\":2,\"c\":[\"foo\"],\"f\":3,\"g\":{}}", json);
 }
 
 }  // namespace trace_event
 }  // namespace base