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/gtest_xctest_wrapper.mm

@@ -0,0 +1,23 @@
+// Copyright 2019 Google LLC. All Rights Reserved.
+
+#import <XCTest/XCTest.h>
+
+#include <gtest/gtest.h>
+
+// Defined in cdm_test_main.cpp.
+int main(int argc, char** argv);
+
+@interface GtestTests : XCTestCase
+@end
+
+@implementation GtestTests
+
+- (void)testAll {
+  testing::GTEST_FLAG(filter) = GTEST_FILTER;
+
+  char arg0[] = "tests";
+  char* argv[] = {arg0, nullptr};
+  XCTAssertEqual(main(1, argv), 0);
+}
+
+@end