Battery Status API: end-to-end browsertests and default values.

content/browser/battery_status/battery_status_service.cc

 // Copyright 2014 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/browser/battery_status/battery_status_service.h"
 
 #include "base/bind.h"
 #include "content/browser/battery_status/battery_status_manager.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace content {
 
 BatteryStatusService::BatteryStatusService()
-    : status_updated_(false),
+    : update_callback_(base::Bind(&BatteryStatusService::UpdateBatteryStatus,
+                                  base::Unretained(this))),
+      status_updated_(false),
       is_shutdown_(false) {
-  update_callback_ = base::Bind(&BatteryStatusService::UpdateBatteryStatus,
-                                base::Unretained(this));
   callback_list_.set_removal_callback(
       base::Bind(&BatteryStatusService::ConsumersChanged,
                  base::Unretained(this)));
 }
 
 BatteryStatusService::~BatteryStatusService() {
 }
 
 BatteryStatusService* BatteryStatusService::GetInstance() {
   return Singleton<BatteryStatusService,
                    LeakySingletonTraits<BatteryStatusService> >::get();
 }
 
 scoped_ptr<BatteryStatusService::BatteryUpdateSubscription>
 BatteryStatusService::AddCallback(const BatteryUpdateCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK(!is_shutdown_);
 
   if (!battery_fetcher_)
     battery_fetcher_.reset(new BatteryStatusManager(update_callback_));
 
-  if (callback_list_.empty())
-    battery_fetcher_->StartListeningBatteryChange();
+  if (callback_list_.empty()) {
+    bool success = battery_fetcher_->StartListeningBatteryChange();
+    if (!success) {
+        // Make sure the promise resolves with the default values in Blink.
+        callback.Run(blink::WebBatteryStatus());
+    }
+  }
 
   if (status_updated_) {
     // Send recent status to the new callback if already available.
     callback.Run(status_);
   }
 
   return callback_list_.Add(callback);
 }
 
 void BatteryStatusService::ConsumersChanged() {
@@ skipping 22 matching lines @@
   if (callback_list_.empty())
     return;
 
   status_ = status;
   status_updated_ = true;
   callback_list_.Notify(status);
 }
 
 void BatteryStatusService::Shutdown() {
   if (!callback_list_.empty())
-      battery_fetcher_->StopListeningBatteryChange();
+    battery_fetcher_->StopListeningBatteryChange();
   battery_fetcher_.reset();
   is_shutdown_ = true;
 }
 
 const BatteryStatusService::BatteryUpdateCallback&
 BatteryStatusService::GetUpdateCallbackForTesting() const {
   return update_callback_;
 }
 
 void BatteryStatusService::SetBatteryManagerForTesting(
     BatteryStatusManager* test_battery_manager) {
   battery_fetcher_.reset(test_battery_manager);
   blink::WebBatteryStatus status;
   status_ = status;
   status_updated_ = false;
 }
 
 }  // namespace content