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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "content/browser/battery_status/battery_status_service.h"
      6 
      7 #include "base/bind.h"
      8 #include "content/browser/battery_status/battery_status_manager.h"
      9 #include "content/public/browser/browser_thread.h"
     10 
     11 namespace content {
     12 
     13 BatteryStatusService::BatteryStatusService()
     14     : update_callback_(base::Bind(&BatteryStatusService::UpdateBatteryStatus,
     15                                   base::Unretained(this))),
     16       status_updated_(false),
     17       is_shutdown_(false) {
     18   callback_list_.set_removal_callback(
     19       base::Bind(&BatteryStatusService::ConsumersChanged,
     20                  base::Unretained(this)));
     21 }
     22 
     23 BatteryStatusService::~BatteryStatusService() {
     24 }
     25 
     26 BatteryStatusService* BatteryStatusService::GetInstance() {
     27   return Singleton<BatteryStatusService,
     28                    LeakySingletonTraits<BatteryStatusService> >::get();
     29 }
     30 
     31 scoped_ptr<BatteryStatusService::BatteryUpdateSubscription>
     32 BatteryStatusService::AddCallback(const BatteryUpdateCallback& callback) {
     33   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     34   DCHECK(!is_shutdown_);
     35 
     36   if (!battery_fetcher_)
     37     battery_fetcher_.reset(new BatteryStatusManager(update_callback_));
     38 
     39   if (callback_list_.empty()) {
     40     bool success = battery_fetcher_->StartListeningBatteryChange();
     41     if (!success) {
     42         // Make sure the promise resolves with the default values in Blink.
     43         callback.Run(blink::WebBatteryStatus());
     44     }
     45   }
     46 
     47   if (status_updated_) {
     48     // Send recent status to the new callback if already available.
     49     callback.Run(status_);
     50   }
     51 
     52   return callback_list_.Add(callback);
     53 }
     54 
     55 void BatteryStatusService::ConsumersChanged() {
     56   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     57   DCHECK(!is_shutdown_);
     58 
     59   if (callback_list_.empty()) {
     60       battery_fetcher_->StopListeningBatteryChange();
     61       status_updated_ = false;
     62   }
     63 }
     64 
     65 void BatteryStatusService::UpdateBatteryStatus(
     66     const blink::WebBatteryStatus& status) {
     67   DCHECK(!is_shutdown_);
     68   BrowserThread::PostTask(BrowserThread::IO,
     69                           FROM_HERE,
     70                           base::Bind(&BatteryStatusService::NotifyConsumers,
     71                                      base::Unretained(this), status));
     72 }
     73 
     74 void BatteryStatusService::NotifyConsumers(
     75     const blink::WebBatteryStatus& status) {
     76   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     77 
     78   if (callback_list_.empty())
     79     return;
     80 
     81   status_ = status;
     82   status_updated_ = true;
     83   callback_list_.Notify(status);
     84 }
     85 
     86 void BatteryStatusService::Shutdown() {
     87   if (!callback_list_.empty())
     88     battery_fetcher_->StopListeningBatteryChange();
     89   battery_fetcher_.reset();
     90   is_shutdown_ = true;
     91 }
     92 
     93 const BatteryStatusService::BatteryUpdateCallback&
     94 BatteryStatusService::GetUpdateCallbackForTesting() const {
     95   return update_callback_;
     96 }
     97 
     98 void BatteryStatusService::SetBatteryManagerForTesting(
     99     BatteryStatusManager* test_battery_manager) {
    100   battery_fetcher_.reset(test_battery_manager);
    101   blink::WebBatteryStatus status;
    102   status_ = status;
    103   status_updated_ = false;
    104 }
    105 
    106 }  // namespace content
    107