Hide empty CPU profile on class page

runtime/observatory/lib/src/elements/cpu_profile.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library cpu_profile_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/service.dart';
@@ skipping 541 matching lines @@
   }
 
   void directionSelectorChanged(oldValue) {
     if (onTreeConfigChange == null) {
       return;
     }
     onTreeConfigChange(modeSelector, directionSelector);
   }
 
   Function onTreeConfigChange;
+  @observable bool show = true;
   @observable bool showModeSelector = true;
   @observable bool showDirectionSelector = true;
   @observable String modeSelector = 'Function';
   @observable String directionSelector = 'Up';
 }
 
 /// Displays a CpuProfile
 @CustomTag('cpu-profile')
 class CpuProfileElement extends ObservatoryElement {
   CpuProfileElement.created() : super.created() {
@@ skipping 546 matching lines @@
 }
 
 @CustomTag('cpu-profile-tree')
 class CpuProfileTreeElement extends ObservatoryElement {
   ProfileTreeDirection direction = ProfileTreeDirection.Exclusive;
   ProfileTreeMode mode = ProfileTreeMode.Function;
   CpuProfile profile;
   TableTree codeTree;
   TableTree functionTree;
   FunctionCallTreeNodeFilter functionFilter;
+  @observable bool show = true;
 
   CpuProfileTreeElement.created() : super.created();
 
   void render() {
     _updateView();
   }
 
+  showChanged(oldValue) {
+    var treeTable = shadowRoot.querySelector('#treeTable');
+    assert(treeTable != null);
+    treeTable.style.display = show ? 'table' : 'none';
+  }
+
   void _updateView() {
     if (functionTree != null) {
       functionTree.clear();
       functionTree = null;
     }
     if (codeTree != null) {
       codeTree.clear();
       codeTree = null;
     }
     bool exclusive = direction == ProfileTreeDirection.Exclusive;
@@ skipping 36 matching lines @@
       return;
     }
     var tree = profile.loadCodeTree(exclusive ? 'exclusive' : 'inclusive');
     if (tree == null) {
       return;
     }
     var rootRow = new CodeProfileTreeRow(codeTree, null, profile, tree.root);
     codeTree.initialize(rootRow);
   }
 }