[DevTools] Do not expose agents on Target

third_party/WebKit/Source/devtools/front_end/sdk/TracingManager.js

 /*
  * 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.
  */
 /**
  * @interface
  */
 SDK.TracingManagerClient = function() {};
 
@@ skipping 12 matching lines @@
    */
   eventsRetrievalProgress(progress) {}
 };
 
 /**
  * @unrestricted
  */
 SDK.TracingManager = class extends SDK.SDKModel {
   /**
    * @param {!SDK.Target} target
+   * @param {!Protocol.Dispatcher} dispatcher
    */
-  constructor(target) {
-    super(target);
-    this._tracingAgent = target.tracingAgent();
-    target.registerTracingDispatcher(new SDK.TracingDispatcher(this));
+  constructor(target, dispatcher) {
+    super(target, dispatcher);
+    this._tracingAgent = dispatcher.tracingAgent();
+    dispatcher.registerTracingDispatcher(new SDK.TracingDispatcher(this));
 
     /** @type {?SDK.TracingManagerClient} */
     this._activeClient = null;
     this._eventBufferSize = 0;
     this._eventsRetrieved = 0;
   }
 
   /**
    * @param {number=} usage
    * @param {number=} eventCount
@@ skipping 105 matching lines @@
     this._tracingManager._eventsCollected(data);
   }
 
   /**
    * @override
    */
   tracingComplete() {
     this._tracingManager._tracingComplete();
   }
 };