Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/rtc_base/zero_memory.h

@@ -0,0 +1,35 @@
+/*
+ *  Copyright 2017 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 RTC_BASE_ZERO_MEMORY_H_
+#define RTC_BASE_ZERO_MEMORY_H_
+
+#include <stddef.h>
+
+#include <type_traits>
+
+#include "api/array_view.h"
+
+namespace rtc {
+
+// Fill memory with zeros in a way that the compiler doesn't optimize it away
+// even if the pointer is not used afterwards.
+void ExplicitZeroMemory(void* ptr, size_t len);
+
+template <typename T,
+          typename std::enable_if<!std::is_const<T>::value &&
+                                  std::is_trivial<T>::value>::type* = nullptr>
+void ExplicitZeroMemory(rtc::ArrayView<T> a) {
+  ExplicitZeroMemory(a.data(), a.size());
+}
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_ZERO_MEMORY_H_