Factor cpu profile tree into separate element and expose allocation tracing UI

runtime/observatory/lib/src/elements/class_view.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 class_view_element;
 
 import 'dart:async';
 import 'observatory_element.dart';
+import 'package:observatory/cpu_profile.dart';
+import 'package:observatory/elements.dart';
 import 'package:observatory/service.dart';
 import 'package:polymer/polymer.dart';
 
 @CustomTag('class-view')
 class ClassViewElement extends ObservatoryElement {
   @published Class cls;
   @observable ServiceMap instances;
   @observable int retainedBytes;
   @observable ObservableList mostRetained;
   ClassViewElement.created() : super.created();
@@ skipping 35 matching lines @@
     mostRetained = null;
     var loads = [];
     loads.add(cls.reload());
     cls.fields.forEach((field) => loads.add(field.reload()));
     return Future.wait(loads);
   }
 
   Future refreshCoverage() {
     return cls.refreshCoverage();
   }
+
+  final CpuProfile profile = new CpuProfile();
+
+  Future refreshAllocationProfile() async {
+    var profileResponse = await cls.getAllocationSamples('UserVM');
+    profile.load(profileResponse.isolate, profileResponse);
+    CpuProfileTreeElement cpuProfileTreeElement =
+        shadowRoot.querySelector('#cpuProfileTree');
+    cpuProfileTreeElement.profile = profile;
+    cpuProfileTreeElement.direction = ProfileTreeDirection.Exclusive;
+    cpuProfileTreeElement.mode = ProfileTreeMode.Function;
+    cpuProfileTreeElement.render();
+  }
+
+  Future toggleAllocationTrace() {
+    if (cls == null) {
+      return new Future(refresh);
+    }
+    return cls.setTraceAllocations(!cls.traceAllocations).whenComplete(refresh);
+  }
 }