Improve Observatory Timeline UI

runtime/observatory/web/timeline_message_handler.js

Index: runtime/observatory/web/timeline_message_handler.js
diff --git a/runtime/observatory/web/timeline_message_handler.js b/runtime/observatory/web/timeline_message_handler.js
new file mode 100644
index 0000000000000000000000000000000000000000..7ae238ded542a0a96c87af53ca877daa9dc84713
--- /dev/null
+++ b/runtime/observatory/web/timeline_message_handler.js
@@ -0,0 +1,49 @@
+// Copyright (c) 2016, 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.
+
+// This file is loaded before the about:tracing code is loaded so that we have
+// an event listener registered early.
+
+// Used to delay the initial timeline load until the timeline has finished
+// loading.
+timeline_loaded = false;
+timeline_vm_address = undefined;
+timeline_isolates = undefined;
+
+function registerForMessages() {
+  window.addEventListener("message", onMessage, false);
+}
+
+registerForMessages();
+
+function onMessage(event) {
+  var request = JSON.parse(event.data);
+  var method = request['method'];
+  var params = request['params'];
+  console.log('method: ' + method)
+  switch (method) {
+    case 'refresh':
+      if (!timeline_loaded) {
+        timeline_vm_address = params['vmAddress'];
+        timeline_isolates = params['isolateIds'];
+        console.log('Delaying timeline refresh until loaded.');
+      } else {
+        fetchTimeline(params['vmAddress'], params['isolateIds']);
+      }
+    break;
+    case 'clear':
+      clearTimeline();
+    break;
+    case 'save':
+      saveTimeline();
+    break;
+    case 'load':
+      loadTimeline();
+    break;
+    default:
+      console.log('Unknown method:' + method + '.');
+  }
+}
+
+console.log('message handler registered');