Update DevTools Tracing.Start to accept trace config as a parameter

base/trace_event/trace_config.cc

Index: base/trace_event/trace_config.cc
diff --git a/base/trace_event/trace_config.cc b/base/trace_event/trace_config.cc
index d60c08124d29be4e5e65395eabec108da00cade8..91b6df19faa88960f62b2464ef0873b39f6b8af9 100644
--- a/base/trace_event/trace_config.cc
+++ b/base/trace_event/trace_config.cc
@@ -72,8 +72,78 @@ class ConvertableTraceConfigToTraceFormat
   const TraceConfig trace_config_;
 };
 
+// Convert each uppercase character to separator + lowercase.
+std::string convertStringStyle(const std::string& in_str,

[Primiano Tucci (use gerrit), 2016/03/06 01:24:37]

This function should not be in base, and once you move it, should have a more
explicative name, such as ToCamelCase ? 

[Primiano Tucci (use gerrit), 2016/03/06 01:24:37]

nit: UpperCase function names:
https://google.github.io/styleguide/cppguide.html#Function_Names

+                               const char& separator) {

[caseq, 2016/03/05 02:25:24]

no need to pass a char by reference :)

+  std::string out_str;
+  for (const char& c : in_str) {
+    if (isupper(c)) {
+      out_str.push_back(separator);
+      out_str.push_back(tolower(c));
+    } else {
+      out_str.push_back(c);
+    }
+  }
+  return out_str;
+}
+
+scoped_ptr<base::Value> convertDictKeyStyle(const base::Value& value) {

[caseq, 2016/03/05 02:25:24]

style: s/convert/Convert/

+  const base::DictionaryValue* dict = NULL;

[caseq, 2016/03/05 02:25:24]

nit: nullptr

+  const base::ListValue* list = NULL;

[caseq, 2016/03/05 02:25:24]

ditto (and please move down to actual usage)

+
+  if (value.GetAsDictionary(&dict)) {
+    scoped_ptr<base::DictionaryValue> out_dict(new base::DictionaryValue());
+    for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd();
+         it.Advance()) {
+      out_dict->Set(convertStringStyle(it.key(), '_'),
+                    convertDictKeyStyle(it.value()));
+    }
+    return std::move(out_dict);
+  } else if (value.GetAsList(&list)) {

[caseq, 2016/03/05 02:25:24]

style: no else after return

+    scoped_ptr<base::ListValue> out_list(new base::ListValue());
+    for (const auto& value : *list) {
+      out_list->Append(convertDictKeyStyle(*value));
+    }
+    return std::move(out_list);
+  } else {

[caseq, 2016/03/05 02:25:24]

ditto.

+    return value.CreateDeepCopy();
+  }
+}
+
 }  // namespace
 
+// static
+scoped_ptr<base::DictionaryValue> TraceConfig::DevToolsToTracingStyle(
+    const scoped_ptr<base::DictionaryValue>& devtools_style) {
+  scoped_ptr<base::Value> value = convertDictKeyStyle(*devtools_style);
+
+  DCHECK(value->IsType(base::Value::TYPE_DICTIONARY));
+  scoped_ptr<base::DictionaryValue> tracing_style(
+      static_cast<base::DictionaryValue*>(value.release()));
+
+  std::string mode;
+  if (tracing_style->GetString(kRecordModeParam, &mode))
+    tracing_style->SetString(kRecordModeParam, convertStringStyle(mode, '-'));
+
+  return tracing_style;
+}
+
+// static
+std::string TraceConfig::DevToolsToTracingStyle(
+    const std::string& devtools_style) {
+  scoped_ptr<Value> value = base::JSONReader::Read(devtools_style);
+  DCHECK(value && value->IsType(base::Value::TYPE_DICTIONARY));
+
+  scoped_ptr<base::DictionaryValue> devtools_style_dict(
+        static_cast<base::DictionaryValue*>(value.release()));
+  scoped_ptr<base::DictionaryValue> tracing_style_dict =
+      DevToolsToTracingStyle(devtools_style_dict);
+
+  std::string tracing_style;
+  base::JSONWriter::Write(*tracing_style_dict, &tracing_style);
+  return tracing_style;
+}
+
 TraceConfig::TraceConfig() {
   InitializeDefault();
 }