DevTools: move UI components to target observers in preparation to early UI initialization.

Source/devtools/front_end/toolbox/ResponsiveDesignView.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
  * @extends {WebInspector.VBox}
  * @implements {WebInspector.OverridesSupport.PageResizer}
+ * @implements {WebInspector.TargetManager.Observer}
  * @param {!WebInspector.InspectedPagePlaceholder} inspectedPagePlaceholder
  */
 WebInspector.ResponsiveDesignView = function(inspectedPagePlaceholder)
 {
     WebInspector.VBox.call(this);
     this.setMinimumSize(150, 150);
     this.element.classList.add("overflow-hidden");
 
     this._responsiveDesignContainer = new WebInspector.VBox();
     this._responsiveDesignContainer.registerRequiredCSS("responsiveDesignView.css");
@@ skipping 37 matching lines @@
     inspectedPagePlaceholder.show(this.element);
 
     this._enabled = false;
     this._viewport = { scrollX: 0, scrollY: 0, contentsWidth: 0, contentsHeight: 0, pageScaleFactor: 1 };
     this._drawContentsSize = true;
     this._viewportChangedThrottler = new WebInspector.Throttler(0);
 
     WebInspector.zoomManager.addEventListener(WebInspector.ZoomManager.Events.ZoomChanged, this._onZoomChanged, this);
     WebInspector.overridesSupport.addEventListener(WebInspector.OverridesSupport.Events.EmulationStateChanged, this._emulationEnabledChanged, this);
     this._mediaInspector.addEventListener(WebInspector.MediaQueryInspector.Events.HeightUpdated, this.onResize, this);
-    WebInspector.resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.ViewportChanged, this._viewportChanged, this);
+    WebInspector.targetManager.observeTargets(this);
 
     this._emulationEnabledChanged();
     this._overridesWarningUpdated();
 };
 
 // Measured in DIP.
 WebInspector.ResponsiveDesignView.SliderWidth = 19;
 WebInspector.ResponsiveDesignView.RulerWidth = 22;
 
 WebInspector.ResponsiveDesignView.prototype = {
+
+    /**
+     * @param {!WebInspector.Target} target
+     */
+    targetAdded: function(target)
+    {
+        // FIXME: adapt this to multiple targets.
+        if (this._target)
+            return;
+        this._target = target;
+        target.resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.ViewportChanged, this._viewportChanged, this);
+    },
+
+    /**
+     * @param {!WebInspector.Target} target
+     */
+    targetRemoved: function(target)
+    {
+        if (target !== this._target)
+            return;
+        target.resourceTreeModel.removeEventListener(WebInspector.ResourceTreeModel.EventTypes.ViewportChanged, this._viewportChanged, this);
+    },
+
     _invalidateCache: function()
     {
         delete this._cachedScale;
         delete this._cachedCssCanvasWidth;
         delete this._cachedCssCanvasHeight;
         delete this._cachedCssHeight;
         delete this._cachedCssWidth;
         delete this._cachedZoomFactor;
         delete this._cachedViewport;
         delete this._cachedDrawContentsSize;
@@ skipping 518 matching lines @@
      * @param {!WebInspector.Throttler.FinishCallback} finishCallback
      */
     _updateUIThrottled: function(finishCallback)
     {
         this._updateUI();
         finishCallback();
     },
 
     __proto__: WebInspector.VBox.prototype
 };