Report utility process JS memory in task manager.

chrome/common/resource_usage_reporter.mojom

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+struct ResourceUsageData {
+  bool reports_v8_stats = false;
+  uint64 v8_bytes_allocated = 0;
+  uint64 v8_bytes_used = 0;
+
+  // TODO(amistry): Consider using this for the renderer process.
+};
+
+interface ResourceUsageReporter {
+  // NOTE: For utility processes, this only reports V8 memory used by the proxy
+  // resolver.
+  GetUsageData() => (ResourceUsageData data);
+};