Converted Observatory debugger elements

runtime/observatory/lib/src/app/page.dart

 // Copyright (c) 2014, 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.
 
 part of app;
 
 final _allocationProfileRepository = new AllocationProfileRepository();
 final _breakpointRepository = new BreakpointRepository();
 final _classSampleProfileRepository = new ClassSampleProfileRepository();
 final _classRepository = new ClassRepository();
@@ skipping 416 matching lines @@
         new ClassTreeElement(app.vm,
                              isolate,
                              app.events,
                              app.notifications,
                              _classRepository)
       ];
     });
   }
 }
 
-class DebuggerPage extends SimplePage {
-  DebuggerPage(app) : super('debugger', 'debugger-page', app);
+class DebuggerPage extends MatchingPage {
+  DebuggerPage(app) : super('debugger', app);
+
+  final DivElement container = new DivElement();
 
   void _visit(Uri uri) {
     super._visit(uri);
-    getIsolate(uri).then((isolate) {
-      if (element != null) {
-        /// Update the page.
-        DebuggerPageElement page = element;
-        page.isolate = isolate;
-      }
+    getIsolate(uri).then((isolate) async {
+      container.children = [
+        new DebuggerPageElement(isolate, _instanceRepository,
+                                _scriptRepository, app.events)
+      ];
     });
   }
+
+  void onInstall() {
+    if (element == null) {
+      element = container;
+    }
+    assert(element != null);
+  }
+
+  @override
+  void onUninstall() {
+    assert(element != null);
+    element.children = const [];
+  }
 }
 
 class ObjectStorePage extends MatchingPage {
   ObjectStorePage(app) : super('object-store', app);
 
   final DivElement container = new DivElement();
 
   void _visit(Uri uri) {
     super._visit(uri);
     getIsolate(uri).then((isolate) async {
@@ skipping 317 matching lines @@
     element = new TimelinePageElement(app.vm, app.events, app.notifications,
                                       queue: app.queue);
   }
 
   void _visit(Uri uri) {
     assert(canVisit(uri));
   }
 
   bool canVisit(Uri uri) => uri.path == 'timeline';
 }