Collect tab timing information for use in telementry-based startup tests

content/common/tab_load_stats.cc

Index: content/common/tab_load_stats.cc
diff --git a/content/common/tab_load_stats.cc b/content/common/tab_load_stats.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e8d860daedd0b9cd48864a9a94ee24ada2ddf90d
--- /dev/null
+++ b/content/common/tab_load_stats.cc
@@ -0,0 +1,29 @@
+// Copyright (c) 2013 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 "content/common/tab_load_stats.h"
+
+#include "base/json/json_writer.h"
+#include "base/values.h"
+
+namespace content {
+
+void ConvertTabLoadTimeToJSON(
+    const content::TabLoadTime& tab_load_time,
+    const base::TimeTicks& timer_start,
+    std::string *result) {
+  DictionaryValue item;
+  base::TimeDelta delta_start = tab_load_time.start_time - timer_start;
+
+  item.SetDouble("load_start_ms", delta_start.InMillisecondsF());
+  if (tab_load_time.stop_time.is_null()) {
+    item.Set("load_stop_ms", Value::CreateNullValue());
+  } else {
+    base::TimeDelta delta_stop = tab_load_time.stop_time - timer_start;
+    item.SetDouble("load_stop_ms", delta_stop.InMillisecondsF());
+  }
+  base::JSONWriter::Write(&item, result);
+}
+
+}  // namespace content