Hide empty CPU profile on class page

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

Index: runtime/observatory/lib/src/elements/cpu_profile.dart
diff --git a/runtime/observatory/lib/src/elements/cpu_profile.dart b/runtime/observatory/lib/src/elements/cpu_profile.dart
index 93ece6626f651f68496b6fc9ed7393ec294b5c2c..97d1fc56c26576a4b49b8f6438b249797714477d 100644
--- a/runtime/observatory/lib/src/elements/cpu_profile.dart
+++ b/runtime/observatory/lib/src/elements/cpu_profile.dart
@@ -559,6 +559,7 @@ class StackTraceTreeConfigElement extends ObservatoryElement {
   }
 
   Function onTreeConfigChange;
+  @observable bool show = true;
   @observable bool showModeSelector = true;
   @observable bool showDirectionSelector = true;
   @observable String modeSelector = 'Function';
@@ -1125,6 +1126,7 @@ class CpuProfileTreeElement extends ObservatoryElement {
   TableTree codeTree;
   TableTree functionTree;
   FunctionCallTreeNodeFilter functionFilter;
+  @observable bool show = true;
 
   CpuProfileTreeElement.created() : super.created();
 
@@ -1132,6 +1134,12 @@ class CpuProfileTreeElement extends ObservatoryElement {
     _updateView();
   }
 
+  showChanged(oldValue) {
+    var treeTable = shadowRoot.querySelector('#treeTable');
+    assert(treeTable != null);
+    treeTable.style.display = show ? 'table' : 'none';
+  }
+
   void _updateView() {
     if (functionTree != null) {
       functionTree.clear();