Add a version of heap snapshots that use only fields and stack frames as roots and only include ins…

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index e0f6e055920eee8fa6b9a594f19a7a0e95bfa2ca..1f5c95f785aecabce40400c3725ae6fcdfd80f44 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -1521,12 +1521,21 @@ class Isolate extends ServiceObjectOwner implements M.Isolate {
     }
   }
 
-  Stream fetchHeapSnapshot(collectGarbage) {
+  static String _rootsToString(M.HeapSnapshotRoots roots) {

[Cutch, 2016/11/28 18:11:12]

I think this works too:

roots.toString().split('.')[1];

[rmacnak, 2016/11/28 22:57:56]

The names don't match. The service enum naming convention is different from the
Dart one.

+    switch (roots) {
+      case M.HeapSnapshotRoots.user: return "User";
+      case M.HeapSnapshotRoots.vm: return "VM";
+    }
+    return null;
+  }
+
+  Stream fetchHeapSnapshot(M.HeapSnapshotRoots roots, bool collectGarbage) {
     if (_snapshotFetch == null || _snapshotFetch.isClosed) {
       _snapshotFetch = new StreamController.broadcast();
       // isolate.vm.streamListen('_Graph');
-      isolate.invokeRpcNoUpgrade(
-          '_requestHeapSnapshot', {'collectGarbage': collectGarbage});
+      isolate.invokeRpcNoUpgrade('_requestHeapSnapshot',
+                                 {'roots': _rootsToString(roots),
+                                  'collectGarbage': collectGarbage});
     }
     return _snapshotFetch.stream;
   }