Created an ArraySize utility function.

[ Merge of http://go/wvgerrit/82232 ]

The new function `ArraySize` will only work for compile-time fixed-length
arrays, and will provide compiler errors if the provided argument is not an
array.

This will replace the commonly used macro `N_ELEM()` which uses `sizeof()`.

Test: Linux unittest
Bug: 137041745
Change-Id: I0f5c268197a8062a99ccba43c73349e97f66eb02

libwvdrmengine/cdm/test/cdm_feature_test.cpp

@@ -26,6 +26,7 @@
 #include <gtest/gtest.h>
 
 #include "OEMCryptoCENC.h"
+#include "arraysize.h"
 #include "config_test_env.h"
 #include "license_protocol.pb.h"
 #include "license_request.h"
@@ -50,8 +51,6 @@ using ::testing::StrictMock;
 
 namespace {
 
-#define N_ELEM(a) (sizeof(a) / sizeof(a[0]))
-
 // HTTP response codes.
 const int kHttpOk = 200;
 // The following two responses are unused, but left here for human debuggers.
@@ -535,7 +534,7 @@ TEST_P(WvCdmSrmTest, Srm) {
 INSTANTIATE_TEST_CASE_P(
     Cdm, WvCdmSrmTest,
     ::testing::Range(&kSrmTestConfiguration[0],
-                     &kSrmTestConfiguration[N_ELEM(kSrmTestConfiguration)]));
+                     &kSrmTestConfiguration[ArraySize(kSrmTestConfiguration)]));
 
 // These parameterized tests validate SRM scenarios described in
 // SRM End-to-End Test Plan doc
@@ -585,6 +584,6 @@ TEST_P(WvCdmSrmNotSupportedTest, Srm) {
 INSTANTIATE_TEST_CASE_P(
     Cdm, WvCdmSrmNotSupportedTest,
     ::testing::Range(&kSrmNotSupportedTestConfiguration[0],
-                     &kSrmNotSupportedTestConfiguration[N_ELEM(
+                     &kSrmNotSupportedTestConfiguration[ArraySize(
                          kSrmNotSupportedTestConfiguration)]));
 }  // namespace wvcdm