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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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