[Startup Tracing] Remove |is_recording_| in devtool tracing_handler

content/browser/devtools/protocol/tracing_handler.h

 // 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 CONTENT_BROWSER_DEVTOOLS_PROTOCOL_TRACING_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_PROTOCOL_TRACING_HANDLER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 36 matching lines @@
   void OnRecordingEnabled(DevToolsCommandId command_id);
   void OnBufferUsage(float percent_full, size_t approximate_event_count);
 
   void OnCategoriesReceived(DevToolsCommandId command_id,
                             const std::set<std::string>& category_set);
 
   void SetupTimer(double usage_reporting_interval);
 
   void DisableRecording(bool abort);
 
+  bool IsRecording() const;
+
   scoped_ptr<base::Timer> buffer_usage_poll_timer_;
   Target target_;
-  bool is_recording_;
 
   scoped_ptr<Client> client_;
   base::WeakPtrFactory<TracingHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TracingHandler);
 };
 
 }  // namespace tracing
 }  // namespace devtools
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_PROTOCOL_TRACING_HANDLER_H_