Add fine grained command line and service protocol control over timeline streams recording

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

Index: runtime/observatory/lib/src/elements/timeline_page.dart
diff --git a/runtime/observatory/lib/src/elements/timeline_page.dart b/runtime/observatory/lib/src/elements/timeline_page.dart
index 04a7376186b8ef6da0113d23d866be987f92bcce..b7a5462d523befc7b363a11358d9ef8f74d8ee24 100644
--- a/runtime/observatory/lib/src/elements/timeline_page.dart
+++ b/runtime/observatory/lib/src/elements/timeline_page.dart
@@ -57,14 +57,14 @@ class TimelinePageElement extends ObservatoryElement {
   }
 
   Future recordOn() async {
-    return app.vm.invokeRpc('_setVMTimelineFlag', {
-      '_record': 'all',
+    return app.vm.invokeRpc('_setVMTimelineFlags', {
+      'recordedStreams': ['all'],
     });
   }
 
   Future recordOff() async {
-    return app.vm.invokeRpc('_setVMTimelineFlag', {
-      '_record': 'none',
+    return app.vm.invokeRpc('_setVMTimelineFlags', {
+      'recordedStreams': [],
     });
   }