Update to current webrtc library

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

webrtc/rtc_base/system/file_wrapper.cc

@@ -0,0 +1,127 @@
+/*
+ *  Copyright (c) 2012 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.
+ */
+
+#include "rtc_base/system/file_wrapper.h"
+#include "rtc_base/numerics/safe_conversions.h"
+
+#include <cerrno>
+
+#ifdef _WIN32
+#include <Windows.h>
+#else
+#include <string.h>
+#endif
+
+#include <utility>
+
+namespace webrtc {
+namespace {
+FILE* FileOpen(const char* file_name_utf8, bool read_only, int* error) {
+#if defined(_WIN32)
+  int len = MultiByteToWideChar(CP_UTF8, 0, file_name_utf8, -1, nullptr, 0);
+  std::wstring wstr(len, 0);
+  MultiByteToWideChar(CP_UTF8, 0, file_name_utf8, -1, &wstr[0], len);
+  FILE* file = _wfopen(wstr.c_str(), read_only ? L"rb" : L"wb");
+#else
+  FILE* file = fopen(file_name_utf8, read_only ? "rb" : "wb");
+#endif
+  if (!file && error) {
+    *error = errno;
+  }
+  return file;
+}
+
+const char* GetCstrCheckNoEmbeddedNul(const std::string& s) {
+  const char* p = s.c_str();
+  RTC_CHECK_EQ(strlen(p), s.size())
+      << "Invalid filename, containing NUL character";
+  return p;
+}
+}  // namespace
+
+// static
+FileWrapper FileWrapper::OpenReadOnly(const char* file_name_utf8) {
+  return FileWrapper(FileOpen(file_name_utf8, true, nullptr));
+}
+
+// static
+FileWrapper FileWrapper::OpenReadOnly(const std::string& file_name_utf8) {
+  return OpenReadOnly(GetCstrCheckNoEmbeddedNul(file_name_utf8));
+}
+
+// static
+FileWrapper FileWrapper::OpenWriteOnly(const char* file_name_utf8,
+                                       int* error /*=nullptr*/) {
+  return FileWrapper(FileOpen(file_name_utf8, false, error));
+}
+
+// static
+FileWrapper FileWrapper::OpenWriteOnly(const std::string& file_name_utf8,
+                                       int* error /*=nullptr*/) {
+  return OpenWriteOnly(GetCstrCheckNoEmbeddedNul(file_name_utf8), error);
+}
+
+FileWrapper::FileWrapper(FileWrapper&& other) {
+  operator=(std::move(other));
+}
+
+FileWrapper& FileWrapper::operator=(FileWrapper&& other) {
+  Close();
+  file_ = other.file_;
+  other.file_ = nullptr;
+  return *this;
+}
+
+bool FileWrapper::SeekRelative(int64_t offset) {
+  RTC_DCHECK(file_);
+  return fseek(file_, rtc::checked_cast<long>(offset), SEEK_CUR) == 0;
+}
+
+bool FileWrapper::SeekTo(int64_t position) {
+  RTC_DCHECK(file_);
+  return fseek(file_, rtc::checked_cast<long>(position), SEEK_SET) == 0;
+}
+
+bool FileWrapper::Flush() {
+  RTC_DCHECK(file_);
+  return fflush(file_) == 0;
+}
+
+size_t FileWrapper::Read(void* buf, size_t length) {
+  RTC_DCHECK(file_);
+  return fread(buf, 1, length, file_);
+}
+
+bool FileWrapper::ReadEof() const {
+  RTC_DCHECK(file_);
+  return feof(file_);
+}
+
+bool FileWrapper::Write(const void* buf, size_t length) {
+  RTC_DCHECK(file_);
+  return fwrite(buf, 1, length, file_) == length;
+}
+
+bool FileWrapper::Close() {
+  if (file_ == nullptr)
+    return true;
+
+  bool success = fclose(file_) == 0;
+  file_ = nullptr;
+  return success;
+}
+
+FILE* FileWrapper::Release() {
+  FILE* file = file_;
+  file_ = nullptr;
+  return file;
+}
+
+}  // namespace webrtc