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| 1 // Copyright 2013 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/wifi_data.h" |
| 6 |
| 7 #include <stddef.h> |
| 8 #include <stdint.h> |
| 9 |
| 10 #include <algorithm> |
| 11 #include <limits> |
| 12 |
| 13 #include "base/logging.h" |
| 14 |
| 15 namespace content { |
| 16 |
| 17 AccessPointData::AccessPointData() |
| 18 : radio_signal_strength(std::numeric_limits<int32_t>::min()), |
| 19 channel(std::numeric_limits<int32_t>::min()), |
| 20 signal_to_noise(std::numeric_limits<int32_t>::min()) {} |
| 21 |
| 22 AccessPointData::~AccessPointData() {} |
| 23 |
| 24 WifiData::WifiData() {} |
| 25 |
| 26 WifiData::WifiData(const WifiData& other) = default; |
| 27 |
| 28 WifiData::~WifiData() {} |
| 29 |
| 30 bool WifiData::DiffersSignificantly(const WifiData& other) const { |
| 31 // More than 4 or 50% of access points added or removed is significant. |
| 32 static const size_t kMinChangedAccessPoints = 4; |
| 33 const size_t min_ap_count = |
| 34 std::min(access_point_data.size(), other.access_point_data.size()); |
| 35 const size_t max_ap_count = |
| 36 std::max(access_point_data.size(), other.access_point_data.size()); |
| 37 const size_t difference_threadhold = std::min(kMinChangedAccessPoints, |
| 38 min_ap_count / 2); |
| 39 if (max_ap_count > min_ap_count + difference_threadhold) |
| 40 return true; |
| 41 // Compute size of intersection of old and new sets. |
| 42 size_t num_common = 0; |
| 43 for (AccessPointDataSet::const_iterator iter = access_point_data.begin(); |
| 44 iter != access_point_data.end(); |
| 45 iter++) { |
| 46 if (other.access_point_data.find(*iter) != |
| 47 other.access_point_data.end()) { |
| 48 ++num_common; |
| 49 } |
| 50 } |
| 51 DCHECK(num_common <= min_ap_count); |
| 52 |
| 53 // Test how many have changed. |
| 54 return max_ap_count > num_common + difference_threadhold; |
| 55 } |
| 56 |
| 57 } // namespace content |
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