(Second attempt at http://codereview.chromium.org/553069/show)...

chrome/browser/geolocation/wifi_data_provider_common.cc

Index: chrome/browser/geolocation/wifi_data_provider_common.cc
===================================================================
--- chrome/browser/geolocation/wifi_data_provider_common.cc	(revision 0)
+++ chrome/browser/geolocation/wifi_data_provider_common.cc	(revision 0)
@@ -0,0 +1,95 @@
+// Copyright 2008, Google Inc.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//  1. Redistributions of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//  2. Redistributions in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//  3. Neither the name of Google Inc. nor the names of its contributors may be
+//     used to endorse or promote products derived from this software without
+//     specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "gears/geolocation/wifi_data_provider_common.h"
+
+#include <assert.h>
+
+#if defined(WIN32) || defined(OS_MACOSX)
+
+#if defined(WIN32)
+#include <windows.h>
+#elif defined(OS_MACOSX)
+#include <CoreFoundation/CoreFoundation.h>
+#include "gears/base/common/string_utils_osx.h"
+#include "gears/base/safari/scoped_cf.h"
+#include "third_party/scoped_ptr/scoped_ptr.h"  // For scoped_array
+#endif
+
+std::string16 MacAddressAsString16(const uint8 mac_as_int[6]) {
+  // mac_as_int is big-endian. Write in byte chunks.
+  // Format is XX-XX-XX-XX-XX-XX.
+  static const char16 *kMacFormatString =
+      STRING16(L"%02x-%02x-%02x-%02x-%02x-%02x");
+#ifdef OS_MACOSX
+  scoped_cftype<CFStringRef> format_string(CFStringCreateWithCharacters(
+      kCFAllocatorDefault,
+      kMacFormatString,
+      std::char_traits<char16>::length(kMacFormatString)));
+  scoped_cftype<CFStringRef> mac_string(CFStringCreateWithFormat(
+      kCFAllocatorDefault,
+      NULL,  // not implemented
+      format_string.get(),
+      mac_as_int[0], mac_as_int[1], mac_as_int[2],
+      mac_as_int[3], mac_as_int[4], mac_as_int[5]));
+  std::string16 mac;
+  CFStringRefToString16(mac_string.get(), &mac);
+  return mac;
+#else
+  char16 mac[18];
+#ifdef DEBUG
+  int num_characters =
+#endif
+      wsprintf(mac, kMacFormatString,
+               mac_as_int[0], mac_as_int[1], mac_as_int[2],
+               mac_as_int[3], mac_as_int[4], mac_as_int[5]);
+  assert(num_characters == 17);
+  return mac;
+#endif
+}
+
+#endif  // WIN32 || OS_MACOSX
+
+#if defined(WIN32) || defined(OS_MACOSX) || defined(LINUX)
+
+// These constants are defined for each platfrom in wifi_data_provider_xxx.cc.
+extern const int kDefaultPollingInterval;
+extern const int kNoChangePollingInterval;
+extern const int kTwoNoChangePollingInterval;
+
+int UpdatePollingInterval(int polling_interval, bool scan_results_differ) {
+  if (scan_results_differ) {
+    return kDefaultPollingInterval;
+  }
+  if (polling_interval == kDefaultPollingInterval) {
+    return kNoChangePollingInterval;
+  } else {
+    assert(polling_interval == kNoChangePollingInterval ||
+           polling_interval == kTwoNoChangePollingInterval);
+    return kTwoNoChangePollingInterval;
+  }
+}
+
+#endif  // WIN32 || OS_MACOSX || LINUX