DevTools: Add showing viewport for Layers3DView.

Source/devtools/front_end/sdk/LayerTreeModel.js

Index: Source/devtools/front_end/sdk/LayerTreeModel.js
diff --git a/Source/devtools/front_end/sdk/LayerTreeModel.js b/Source/devtools/front_end/sdk/LayerTreeModel.js
index d76d2ca8a371a7f05ba84d0bbafd42296a476a04..44a863cc0ace6deab2eec70a043a149ccc5b8821 100644
--- a/Source/devtools/front_end/sdk/LayerTreeModel.js
+++ b/Source/devtools/front_end/sdk/LayerTreeModel.js
@@ -251,6 +251,22 @@ WebInspector.LayerTreeBase.prototype = {
         }
     },
 
+    /**
+     * @param {!Object} viewportSize
+     */
+    setViewportSize: function(viewportSize)
+    {
+        this._viewportSize = viewportSize;
+    },
+
+    /**
+     * @return {!Object | undefined}
+     */
+    viewportSize: function()
+    {
+        return this._viewportSize;
+    },
+
     __proto__: WebInspector.TargetAwareObject.prototype
 };
 
@@ -1118,11 +1134,13 @@ WebInspector.DeferredAgentLayerTree.prototype = {
  * @extends {WebInspector.DeferredLayerTree}
  * @param {!WebInspector.Target} target
  * @param {!WebInspector.TracingLayerPayload} root
+ * @param {!Object} viewportSize
  */
-WebInspector.DeferredTracingLayerTree = function(target, root)
+WebInspector.DeferredTracingLayerTree = function(target, root, viewportSize)
 {
     WebInspector.DeferredLayerTree.call(this, target);
     this._root = root;
+    this._viewportSize = viewportSize;
 }
 
 WebInspector.DeferredTracingLayerTree.prototype = {
@@ -1132,6 +1150,7 @@ WebInspector.DeferredTracingLayerTree.prototype = {
     resolve: function(callback)
     {
         var result = new WebInspector.TracingLayerTree(this._target);
+        result.setViewportSize(this._viewportSize);
         result.setLayers(this._root, callback.bind(null, result));
     },