Avoid using ToInternalValue in computing timings, so that the timings are consistent accross platfo…

content/renderer/stats_collection_controller.cc

 // Copyright 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/renderer/stats_collection_controller.h"
 
 #include "base/json/json_writer.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/strings/string_util.h"
@@ skipping 29 matching lines @@
 }
 
 // Encodes a WebContentsLoadTime as JSON.
 // Input:
 // - |load_start_time| - time at which page load started.
 // - |load_stop_time| - time at which page load stopped.
 // - |result| - returned JSON.
 // Example return value:
 // {'load_start_ms': 1, 'load_duration_ms': 2.5}
 // either value may be null if a web contents hasn't fully loaded.
-// load_start_ms is represented as milliseconds since system boot.
+// load_start_ms is represented as milliseconds since the unix epoch.
 void ConvertLoadTimeToJSON(
     const base::Time& load_start_time,
     const base::Time& load_stop_time,
     std::string *result) {
   base::DictionaryValue item;
 
   if (load_start_time.is_null()) {
     item.Set("load_start_ms", base::Value::CreateNullValue());
   } else {
-    item.SetDouble("load_start_ms", load_start_time.ToInternalValue() / 1000);
+    item.SetDouble("load_start_ms", (load_start_time - base::Time::UnixEpoch())
+                   .InMillisecondsF());
   }
   if (load_start_time.is_null() || load_stop_time.is_null()) {
     item.Set("load_duration_ms", base::Value::CreateNullValue());
   } else {
     item.SetDouble("load_duration_ms",
         (load_stop_time - load_start_time).InMillisecondsF());
   }
   base::JSONWriter::Write(&item, result);
 }
 
@@ skipping 79 matching lines @@
   }
 
   std::string tab_timing_json;
   ConvertLoadTimeToJSON(
       observer->load_start_time(), observer->load_stop_time(),
       &tab_timing_json);
   return tab_timing_json;
 }
 
 }  // namespace content