Observatory: Report peak process memory usage.

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 525b1b7d1402b7e3ef217b6bb521bf87f984b884..675a08e4676391c5f24d89f6c37e1c4cf6610b10 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -630,6 +630,7 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
   @observable bool assertsEnabled = false;
   @observable bool typeChecksEnabled = false;
   @observable int pid = 0;
+  @observable int maxRSS = 0;
   @observable bool profileVM = false;
   @observable DateTime startTime;
   @observable DateTime refreshTime;
@@ -907,6 +908,7 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
     refreshTime = new DateTime.now();
     notifyPropertyChange(#upTime, 0, 1);
     pid = map['pid'];
+    maxRSS = map['_maxRSS'];
     profileVM = map['_profilerMode'] == 'VM';
     assertsEnabled = map['_assertsEnabled'];
     typeChecksEnabled = map['_typeChecksEnabled'];