Add a histogram to measure browser window display

chrome/common/startup_metric_utils.cc

+// Copyright (c) 2012 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.
+
+#include "chrome/common/startup_metric_utils.h"
+
+namespace {
+
+// Value may potentially be modified and read on different threads.

[sky, 2012/07/28 02:13:35]

Is this comment right? Isn't this only used on the UI thread?

+static volatile bool g_non_browser_ui_displayed = false;
+
+}  // namespace
+
+namespace startup_metric_utils {
+
+bool WasNonBrowserUIDisplayed() {
+  return g_non_browser_ui_displayed;
+}
+
+void SetNonBrowserUIDisplayed() {
+  g_non_browser_ui_displayed = true;
+}
+
+}  // namespace startup_metric_utils