Cherry pick 18.4 changes to udc-widevine-dev

Get the udc-widevine-dev Android branch and oemcrypto-v18 cdm branch in
sync. The commit ID for 18.4 on oemcrypto-v18 is
a2f23a2281e5e06dc2867585bdc516fa132b6396.

Merged from go/wvgerrit/190151

Bug: 290252845
Test: WVTS tests are running and passing
Change-Id: I457332e7ca70a5b5169345e1279b3eb9f18413b6

libwvdrmengine/cdm/test/level3_file_system_ce_test.cpp

@@ -0,0 +1,64 @@
+// Copyright 2022 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+
+/**
+   The test file system for the Level 3 OEMCrypto sits on top of the host file
+   system. A real production version may either use the host file system or it
+   may write files directly to the file system.
+ */
+
+#include <algorithm>
+#include <cstring>
+#include <map>
+#include <string>
+
+#include "level3_file_system_ce_test.h"
+
+#include "test_host.h"
+
+namespace wvoec3 {
+
+ssize_t OEMCrypto_Level3CETestFileSystem::Read(const char* filename,
+                                               void* buffer, size_t size) {
+  if (!g_host) return 0;
+  const std::string name(filename);
+  if (!g_host->global_storage().exists(name)) return 0;
+  std::string data;
+  if (!g_host->global_storage().read(name, &data)) return 0;
+  size_t bytes_read = std::min(size, data.size());
+  memcpy(buffer, data.data(), bytes_read);
+  return bytes_read;
+}
+
+ssize_t OEMCrypto_Level3CETestFileSystem::Write(const char* filename,
+                                                const void* buffer,
+                                                size_t size) {
+  if (!g_host) return 0;
+  std::string data(static_cast<const char*>(buffer), size);
+  const std::string name(filename);
+  if (!g_host->global_storage().write(name, data)) return 0;
+  return size;
+}
+
+bool OEMCrypto_Level3CETestFileSystem::Exists(const char* filename) {
+  if (!g_host) return false;
+  const std::string name(filename);
+  return g_host->global_storage().exists(name);
+}
+
+ssize_t OEMCrypto_Level3CETestFileSystem::FileSize(const char* filename) {
+  if (!g_host) return 0;
+  const std::string name(filename);
+  if (!g_host->global_storage().exists(name)) return 0;
+  return static_cast<ssize_t>(g_host->global_storage().size(name));
+}
+
+bool OEMCrypto_Level3CETestFileSystem::Remove(const char* filename) {
+  if (!g_host) return false;
+  const std::string name(filename);
+  if (!g_host->global_storage().exists(name)) return false;
+  return g_host->global_storage().remove(name);
+}
+
+}  // namespace wvoec3