DevTools: introduce multitarget model listeners

Source/devtools/front_end/components/ExecutionContextSelector.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.
 
 /**
  * @constructor
  * @implements {WebInspector.TargetManager.Observer}
  */
 WebInspector.ExecutionContextSelector = function()
 {
     WebInspector.targetManager.observeTargets(this);
     WebInspector.context.addFlavorChangeListener(WebInspector.ExecutionContext, this._executionContextChanged, this);
     WebInspector.context.addFlavorChangeListener(WebInspector.Target, this._targetChanged, this);
+
+    WebInspector.targetManager.addModelListener(WebInspector.RuntimeModel, WebInspector.RuntimeModel.Events.ExecutionContextCreated, this._onExecutionContextCreated, this);
+    WebInspector.targetManager.addModelListener(WebInspector.RuntimeModel, WebInspector.RuntimeModel.Events.ExecutionContextDestroyed, this._onExecutionContextDestroyed, this);
 }
 
 WebInspector.ExecutionContextSelector.prototype = {
 
     /**
      * @param {!WebInspector.Target} target
      */
     targetAdded: function(target)
     {
         if (!WebInspector.context.flavor(WebInspector.Target))
             WebInspector.context.setFlavor(WebInspector.Target, target);
-
-        target.runtimeModel.addEventListener(WebInspector.RuntimeModel.Events.ExecutionContextCreated, this._onExecutionContextCreated, this);
-        target.runtimeModel.addEventListener(WebInspector.RuntimeModel.Events.ExecutionContextDestroyed, this._onExecutionContextDestroyed, this);
     },
 
     /**
      * @param {!WebInspector.Target} target
      */
     targetRemoved: function(target)
     {
-        target.runtimeModel.removeEventListener(WebInspector.RuntimeModel.Events.ExecutionContextCreated, this._onExecutionContextCreated, this);
-        target.runtimeModel.removeEventListener(WebInspector.RuntimeModel.Events.ExecutionContextDestroyed, this._onExecutionContextDestroyed, this);
         var currentExecutionContext = WebInspector.context.flavor(WebInspector.ExecutionContext);
         if (currentExecutionContext && currentExecutionContext.target() === target)
             this._currentExecutionContextGone();
 
         var targets = WebInspector.targetManager.targets();
         if (WebInspector.context.flavor(WebInspector.Target) === target && targets.length)
             WebInspector.context.setFlavor(WebInspector.Target, targets[0]);
     },
 
     /**
@@ skipping 78 matching lines @@
         completionsReadyCallback([]);
         return;
     }
 
     // Pass less stop characters to rangeOfWord so the range will be a more complete expression.
     var expressionRange = wordRange.startContainer.rangeOfWord(wordRange.startOffset, " =:[({;,!+-*/&|^<>", proxyElement, "backward");
     var expressionString = expressionRange.toString();
     var prefix = wordRange.toString();
     executionContext.completionsForExpression(expressionString, prefix, force, completionsReadyCallback);
 }