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

content/common/tab_load_stats.h

+// 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.
+
+#ifndef CONTENT_COMMON_TAB_LOAD_STATS_H_
+#define CONTENT_COMMON_TAB_LOAD_STATS_H_
+
+#include <string>
+#include <vector>
+
+#include "base/time.h"
+
+namespace content {
+
+// Holds onto start and stop timestamps for a particular tab.
+struct TabLoadTime {

[jam, 2013/04/04 17:28:39]

tab is a chrome concept, content doesn't know about them.

this should be related to web contents

[jeremy, 2013/04/07 14:51:54]

Renamed tab -> web_contents globally.

+ public:
+  TabLoadTime() {}
+
+  explicit TabLoadTime(base::TimeTicks started)
+      : start_time(started) {
+  }
+
+  ~TabLoadTime() {}
+
+  void set_stop_time(base::TimeTicks stopped) {
+    stop_time = stopped;
+  }
+
+  base::TimeTicks start_time;
+  base::TimeTicks stop_time;
+};
+
+// Encodes a TabLoadTime as JSON.
+// Input:
+// - |tab_load_time| - data to encode.
+// - |timer_start| - clock start, output times are recorded as deltas from this
+//                   point in time.
+// - |result| - returned JSON.
+// Example return value:
+// {'start_time_ms': 1, 'stop_time_ms': 2.5}
+// stop_time_ms values may be null if a tab hasn't fully loaded.
+void ConvertTabLoadTimeToJSON(

[jam, 2013/04/04 17:28:39]

this method is only called in the renderer. why is it in content\common?

[jeremy, 2013/04/07 14:51:54]

Done.

+    const content::TabLoadTime& tab_load_time,
+    const base::TimeTicks& timer_start,
+    std::string *result);
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_TAB_LOAD_STATS_H_