Add RPC and UI for reachable size of an object / all instances of a class.

runtime/observatory/tests/service/reachable_size_test.dart

+// Copyright (c) 2015, 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.
+// VMOptions=--error_on_bad_type --error_on_bad_override
+
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+
+class Pair {
+  var x, y;
+}
+
+var p1;
+var p2;
+
+buildGraph() {
+  p1 = new Pair();
+  p2 = new Pair();
+
+  // Adds to both reachable and retained size.
+  p1.x = new List();
+  p2.x = new List();
+
+  // Adds to reachable size only.
+  p1.y = p2.y = new List();
+}
+
+getReachableSize(ServiceObject obj) {
+  return obj.isolate.getReachableSize(obj).then((Instance obj) {
+    return int.parse(obj.valueAsString);
+  });
+}
+
+getRetainedSize(ServiceObject obj) {
+  return obj.isolate.getRetainedSize(obj).then((Instance obj) {
+    return int.parse(obj.valueAsString);
+  });
+}
+
+var tests = [
+(Isolate isolate) async {
+  Instance p1 = await rootLibraryFieldValue(isolate, "p1");
+  Instance p2 = await rootLibraryFieldValue(isolate, "p2");
+
+  // In general, shallow <= retained <= reachable. In this program,
+  // 0 < shallow < retained < reachable.
+
+  int p1_shallow = p1.size;
+  int p1_retained = await getRetainedSize(p1);
+  int p1_reachable = await getReachableSize(p1);
+
+  expect(0, lessThan(p1_shallow));
+  expect(p1_shallow, lessThan(p1_retained));
+  expect(p1_retained, lessThan(p1_reachable));
+
+  int p2_shallow = p2.size;
+  int p2_retained = await getRetainedSize(p2);
+  int p2_reachable = await getReachableSize(p2);
+
+  expect(0, lessThan(p2_shallow));
+  expect(p2_shallow, lessThan(p2_retained));
+  expect(p2_retained, lessThan(p2_reachable));
+
+  expect(p1_shallow, equals(p2_shallow));
+  expect(p1_retained, equals(p2_retained));
+  expect(p1_reachable, equals(p2_reachable));
+},
+];
+
+main(args) => runIsolateTests(args, tests, testeeBefore: buildGraph);