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

base/trace_event/trace_config.h

 // Copyright 2015 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_TRACE_EVENT_TRACE_CONFIG_H_
 #define BASE_TRACE_EVENT_TRACE_CONFIG_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 31 matching lines @@
 
   // Specifies the memory dump config for tracing. Used only when
   // "memory-infra" category is enabled.
   struct MemoryDumpTriggerConfig {
     uint32_t periodic_interval_ms;
     MemoryDumpLevelOfDetail level_of_detail;
   };
 
   typedef std::vector<MemoryDumpTriggerConfig> MemoryDumpConfig;
 
+  // Convert from DevTools style to tracing style. That is:
+  // 1. Convert dict key style: abcDefGhi => abc_def_ghi.
+  //    For example: includedCategories => included_categories
+  // 2. Convert trace record mode style: abcDefGhi => abc-def-ghi.
+  //    For example: recordUntilFull => record-until-full
+  static scoped_ptr<base::DictionaryValue> DevToolsToTracingStyle(

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

I think it would be better out of base -- doing this in DevTools or tracing
controller would be the best perhaps.

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

+1. Base should not know anything about devtools.

+      const scoped_ptr<base::DictionaryValue>& devtools_style);
+  static std::string DevToolsToTracingStyle(const std::string& devtools_style);
+
   TraceConfig();
 
   // Create TraceConfig object from category filter and trace options strings.
   //
   // |category_filter_string| is a comma-delimited list of category wildcards.
   // A category can have an optional '-' prefix to make it an excluded category.
   // All the same rules apply above, so for example, having both included and
   // excluded categories in the same list would not be supported.
   //
   // Category filters can also be used to configure synthetic delays.
@@ skipping 174 matching lines @@
   StringList included_categories_;
   StringList disabled_categories_;
   StringList excluded_categories_;
   StringList synthetic_delays_;
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_CONFIG_H_