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

third_party/WebKit/Source/web/WebDevToolsAgentImpl.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 99 matching lines @@
     void dispatchOnInspectorBackend(int sessionId, const WebString& message) override;
     void inspectElementAt(const WebPoint&) override;
     void failedToRequestDevTools() override;
     void evaluateInWebInspector(long callId, const WebString& script) override;
     WebString evaluateInWebInspectorOverlay(const WebString& script) override;
 
 private:
     WebDevToolsAgentImpl(WebLocalFrameImpl*, WebDevToolsAgentClient*, PassOwnPtrWillBeRawPtr<InspectorOverlay>);
 
     // InspectorTracingAgent::Client implementation.
+    void enableTracingWithConfigStr(const String& devtoolsStyleConfig) override;

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

Having to do all this plumbing is quite unfortunate. I'll see if I can help here
by removing the need for starting tracing from renderer.

     void enableTracing(const WTF::String& categoryFilter) override;
     void disableTracing() override;
 
     // InspectorEmulationAgent::Client implementation.
     void setCPUThrottlingRate(double) override;
 
     // InspectorRuntimeAgent::Client implementation.
     void resumeStartup() override;
     bool didCommitLoadFired() override;
 
@@ skipping 48 matching lines @@
     int m_sessionId;
     String m_stateCookie;
     bool m_stateMuted;
 
     friend class DebuggerTask;
 };
 
 } // namespace blink
 
 #endif