[chromeos] Add a battery discharge rate plot to about:power page.

chromeos/power/power_data_collector.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 "chromeos/power/power_data_collector.h"
 
 #include "base/logging.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/power_manager/power_supply_properties.pb.h"
 
@@ skipping 31 matching lines @@
   return g_power_data_collector;
 }
 
 void PowerDataCollector::PowerChanged(
     const power_manager::PowerSupplyProperties& prop) {
   PowerSupplySnapshot snapshot;
   snapshot.time = base::TimeTicks::Now();
   snapshot.external_power = (prop.external_power() !=
       power_manager::PowerSupplyProperties::DISCONNECTED);
   snapshot.battery_percent = prop.battery_percent();
+  snapshot.battery_discharge_rate = prop.battery_discharge_rate();
   AddSnapshot(snapshot);
 }
 
 PowerDataCollector::PowerDataCollector() {
   DBusThreadManager::Get()->GetPowerManagerClient()->AddObserver(this);
 }
 
 PowerDataCollector::~PowerDataCollector() {
   DBusThreadManager* dbus_manager = DBusThreadManager::Get();
   CHECK(dbus_manager);
   dbus_manager->GetPowerManagerClient()->RemoveObserver(this);
 }
 
 void PowerDataCollector::AddSnapshot(const PowerSupplySnapshot& snapshot) {
   while (!power_supply_data_.empty()) {
     const PowerSupplySnapshot& first = power_supply_data_.front();
     if (snapshot.time - first.time >
         base::TimeDelta::FromSeconds(kSampleTimeLimitSec)) {
       power_supply_data_.pop_front();
     } else {
       break;
     }
   }
   power_supply_data_.push_back(snapshot);
 }
 
 PowerDataCollector::PowerSupplySnapshot::PowerSupplySnapshot()
     : time(base::TimeTicks::Now()),
       external_power(false),
-      battery_percent(0) {
+      battery_percent(0),
+      battery_discharge_rate(0.0) {
 }
 
 }  // namespace chromeos