Reland 1531763006

Enable IPv6 temporary address filtering on iOS.

We'll only use temporary address for IPv6. However, due to a bug in iOS sdk, the necessary headers are not included. This change copies the minimum necessary definitions such that we could retrieve the ip attributes.

BUG=webrtc:4343

Committed: https://crrev.com/29488c23644721c10a45eba74c67602b0262e582
Cr-Commit-Position: refs/heads/master@{#11114}

patch from issue 1531763006 at patchset 200001 (http://crrev.com/1531763006#ps200001)

TBR=pthatcher@webrtc.org

Review URL: https://codereview.webrtc.org/1551703002 .

Cr-Commit-Position: refs/heads/master@{#11133}
diff --git a/webrtc/base/ifaddrs_converter.h b/webrtc/base/ifaddrs_converter.h
new file mode 100644
index 0000000..0a1cdb9
--- /dev/null
+++ b/webrtc/base/ifaddrs_converter.h
@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_IFADDRS_CONVERTER_H_
+#define WEBRTC_BASE_IFADDRS_CONVERTER_H_
+
+#if defined(WEBRTC_ANDROID)
+#include "webrtc/base/ifaddrs-android.h"
+#else
+#include <ifaddrs.h>
+#endif  // WEBRTC_ANDROID
+
+#include "webrtc/base/ipaddress.h"
+
+namespace rtc {
+
+// This class converts native interface addresses to our internal IPAddress
+// class. Subclasses should override ConvertNativeToIPAttributes to implement
+// the different ways of retrieving IPv6 attributes for various POSIX platforms.
+class IfAddrsConverter {
+ public:
+  IfAddrsConverter();
+  virtual ~IfAddrsConverter();
+  virtual bool ConvertIfAddrsToIPAddress(const struct ifaddrs* interface,
+                                         InterfaceAddress* ipaddress,
+                                         IPAddress* mask);
+
+ protected:
+  virtual bool ConvertNativeAttributesToIPAttributes(
+      const struct ifaddrs* interface,
+      int* ip_attributes);
+};
+
+IfAddrsConverter* CreateIfAddrsConverter();
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_IFADDRS_CONVERTER_H_