Add 'Sockets' to observatory.

runtime/bin/vmservice/client/lib/src/elements/io_view.dart

Index: runtime/bin/vmservice/client/lib/src/elements/io_view.dart
diff --git a/runtime/bin/vmservice/client/lib/src/elements/io_view.dart b/runtime/bin/vmservice/client/lib/src/elements/io_view.dart
index a3daa082a258455fda34eae6ca4e51fbc80afc68..24c137a6d445a0cd0ae231c905e04fe9bd964986 100644
--- a/runtime/bin/vmservice/client/lib/src/elements/io_view.dart
+++ b/runtime/bin/vmservice/client/lib/src/elements/io_view.dart
@@ -77,6 +77,17 @@ class IOSocketRefElement extends ServiceRefElement {
   IOSocketRefElement.created() : super.created();
 }
 
+@CustomTag('io-socket-list-view')
+class IOSocketListViewElement extends ObservatoryElement {
+  @published ServiceMap list;
+
+  IOSocketListViewElement.created() : super.created();
+
+  void refresh(var done) {
+    list.reload().whenComplete(done);
+  }
+}
+
 @CustomTag('io-socket-view')
 class IOSocketViewElement extends ObservatoryElement {
   @published ServiceMap socket;