1 // Copyright (c) 2012 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/geolocation/device_data_provider.h" 6 7 namespace content { 8 9 // statics 10 template<> DeviceDataProvider<WifiData>* 11 DeviceDataProvider<WifiData>::instance_ = NULL; 12 template<> DeviceDataProvider<WifiData>::ImplFactoryFunction 13 DeviceDataProvider<WifiData>::factory_function_ = DefaultFactoryFunction; 14 15 AccessPointData::AccessPointData() 16 : radio_signal_strength(kint32min), 17 channel(kint32min), 18 signal_to_noise(kint32min) { 19 } 20 21 AccessPointData::~AccessPointData() {} 22 23 WifiData::WifiData() {} 24 25 WifiData::~WifiData() {} 26 27 bool WifiData::DiffersSignificantly(const WifiData& other) const { 28 // More than 4 or 50% of access points added or removed is significant. 29 static const size_t kMinChangedAccessPoints = 4; 30 const size_t min_ap_count = 31 std::min(access_point_data.size(), other.access_point_data.size()); 32 const size_t max_ap_count = 33 std::max(access_point_data.size(), other.access_point_data.size()); 34 const size_t difference_threadhold = std::min(kMinChangedAccessPoints, 35 min_ap_count / 2); 36 if (max_ap_count > min_ap_count + difference_threadhold) 37 return true; 38 // Compute size of interesction of old and new sets. 39 size_t num_common = 0; 40 for (AccessPointDataSet::const_iterator iter = access_point_data.begin(); 41 iter != access_point_data.end(); 42 iter++) { 43 if (other.access_point_data.find(*iter) != 44 other.access_point_data.end()) { 45 ++num_common; 46 } 47 } 48 DCHECK(num_common <= min_ap_count); 49 50 // Test how many have changed. 51 return max_ap_count > num_common + difference_threadhold; 52 } 53 54 } // namespace content 55
