text: // 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 "device/geolocation/wifi_data_provider.h"
  
  #include "base/bind.h"
  #include "base/callback.h"
  #include "base/location.h"
  #include "base/threading/thread_task_runner_handle.h"
  
  namespace device {
  
  WifiDataProvider::WifiDataProvider()
      : client_task_runner_(base::ThreadTaskRunnerHandle::Get()) {
    DCHECK(client_task_runner_);
  }
  
  WifiDataProvider::~WifiDataProvider() = default;
  
  void WifiDataProvider::AddCallback(WifiDataUpdateCallback* callback) {
    callbacks_.insert(callback);
  }
  
  bool WifiDataProvider::RemoveCallback(WifiDataUpdateCallback* callback) {
    return callbacks_.erase(callback) == 1;
  }
  
  bool WifiDataProvider::has_callbacks() const {
    return !callbacks_.empty();
  }
  
  void WifiDataProvider::RunCallbacks() {
    client_task_runner_->PostTask(
        FROM_HERE, base::BindOnce(&WifiDataProvider::DoRunCallbacks, this));
  }
  
  bool WifiDataProvider::CalledOnClientThread() const {
    return client_task_runner()->BelongsToCurrentThread();
  }
  
  void WifiDataProvider::DoRunCallbacks() {
    // It's possible that all the callbacks went away whilst this task was
    // pending. This is fine; the loop will be a no-op.
    CallbackSet::const_iterator iter = callbacks_.begin();
    while (iter != callbacks_.end()) {
      WifiDataUpdateCallback* callback = *iter;
      ++iter;  // Advance iter before running, in case callback unregisters.
      callback->Run();
    }
  }
  
  }  // namespace device
  