[DevTools] Do not expose agents on Target

third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js

Index: third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js b/third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js
index c39653bb4ca4794ed60fc24ea43409740045e794..42030bad1a6a1d45fca7509c42cf33ee5e88c882 100644
--- a/third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js
+++ b/third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js
@@ -32,10 +32,14 @@
  * @unrestricted
  */
 Layers.LayerTreeModel = class extends SDK.SDKModel {
-  constructor(target) {
-    super(target);
-    this._layerTreeAgent = target.layerTreeAgent();
-    target.registerLayerTreeDispatcher(new Layers.LayerTreeDispatcher(this));
+  /**
+   * @param {!SDK.Target} target
+   * @param {!Protocol.Dispatcher} dispatcher
+   */
+  constructor(target, dispatcher) {
+    super(target, dispatcher);
+    this._layerTreeAgent = dispatcher.layerTreeAgent();
+    dispatcher.registerLayerTreeDispatcher(new Layers.LayerTreeDispatcher(this));
     this._paintProfilerModel = /** @type {!SDK.PaintProfilerModel} */ (target.model(SDK.PaintProfilerModel));
     var resourceTreeModel = target.model(SDK.ResourceTreeModel);
     if (resourceTreeModel) {