chromeos: Fix a bug in the battery-time-rounding code.

ash/system/chromeos/power/power_status.cc

 // 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 "ash/system/chromeos/power/power_status.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "ash/shell.h"
@@ skipping 99 matching lines @@
   return time >= base::TimeDelta::FromMinutes(1) &&
       time.InSeconds() <= kMaxBatteryTimeToDisplaySec;
 }
 
 // static
 void PowerStatus::SplitTimeIntoHoursAndMinutes(const base::TimeDelta& time,
                                                int* hours,
                                                int* minutes) {
   DCHECK(hours);
   DCHECK(minutes);
-  *hours = time.InHours();
-  const double seconds =
-      (time - base::TimeDelta::FromHours(*hours)).InSecondsF();
-  *minutes = static_cast<int>(seconds / 60.0 + 0.5);
+  const int total_minutes = static_cast<int>(time.InSecondsF() / 60 + 0.5);
+  *hours = total_minutes / 60;
+  *minutes = total_minutes % 60;
 }
 
 void PowerStatus::AddObserver(Observer* observer) {
   DCHECK(observer);
   observers_.AddObserver(observer);
 }
 
 void PowerStatus::RemoveObserver(Observer* observer) {
   DCHECK(observer);
   observers_.RemoveObserver(observer);
@@ skipping 163 matching lines @@
 }
 
 void PowerStatus::PowerChanged(
     const power_manager::PowerSupplyProperties& proto) {
   proto_ = proto;
   SanitizeProto(&proto_);
   FOR_EACH_OBSERVER(Observer, observers_, OnPowerStatusChanged());
 }
 
 }  // namespace ash