Add request tracing to Observatory:

runtime/bin/vmservice/client/lib/src/app/application.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.
 
 part of app;
 
 /// The observatory application. Instances of this are created and owned
 /// by the observatory_application custom element.
 class ObservatoryApplication extends Observable {
   static ObservatoryApplication app;
@@ skipping 16 matching lines @@
       Logger.root.info('Registering new VM callbacks');
       vm.onConnect.then(_vmConnected);
       vm.onDisconnect.then(_vmDisconnected);
       vm.errors.stream.listen(_onError);
       vm.events.stream.listen(_onEvent);
       vm.exceptions.stream.listen(_onException);
     }
     _vm = vm;
   }
   final TargetManager targets;
-  @observable Isolate isolate;
   @reflectable final ObservatoryApplicationElement rootElement;
 
+  TraceViewElement _traceView = null;
+
   @reflectable ServiceObject lastErrorOrException;
   @observable ObservableList<ServiceEvent> notifications =
       new ObservableList<ServiceEvent>();
 
   void _initOnce(bool chromium) {
     assert(app == null);
     app = this;
     _registerPages();
     locationManager._init(this);
   }
@@ skipping 68 matching lines @@
     }
   }
 
   void _visit(String url, String args) {
     var argsMap;
     if (args == null) {
       argsMap = {};
     } else {
       argsMap = Uri.splitQueryString(args);
     }
+    if (argsMap['trace'] != null) {
+      var traceArg = argsMap['trace'];
+      if (traceArg == 'on') {
+        Tracer.start();
+      } else if (traceArg == 'off') {
+        Tracer.stop();
+      }
+    }
+    if (Tracer.current != null) {
+      Tracer.current.reset();
+    }
+    if (_traceView != null) {
+      _traceView.tracer = Tracer.current;
+    }
     for (var i = 0; i < _pageRegistry.length; i++) {
       var page = _pageRegistry[i];
       if (page.canVisit(url)) {
         _installPage(page);
         page.visit(url, argsMap);
         return;
       }
     }
     throw new FallThroughError();
   }
@@ skipping 12 matching lines @@
       rootElement.children.clear();
     }
     Logger.root.info('Installing page: $page');
     try {
       page.onInstall();
     } catch (e) {
       Logger.root.severe('Failed to install page: $e');
     }
     // Add new page.
     rootElement.children.add(page.element);
+
+    // Add tracing support.
+    print("ADDING TraceView");

[Cutch, 2014/07/30 18:20:46]

remove (or turn into log call) before commit 

[turnidge, 2014/07/30 19:28:15]

Removed.

+    _traceView = new Element.tag('trace-view');
+    _traceView.tracer = Tracer.current;
+    rootElement.children.add(_traceView);
+
     // Remember page.
     currentPage = page;
   }
 
   ObservatoryApplication.devtools(this.rootElement) :
       locationManager = new HashLocationManager(),
       targets = null {
     vm = new PostMessageVM();
     _initOnce(true);
   }
@@ skipping 13 matching lines @@
 
   _vmDisconnected(VM vm) {
     if (this.vm != vm) {
       // This disconnect event occured *after* a new VM was installed.
       return;
     }
     this.vm = null;
     locationManager.go(locationManager.makeLink('/vm-connect/'));
   }
 }