Permit reading /System/Library/CoreServices/SystemVersionCompat.plist in the sandbox.

This is a new file on macOS 11 Big Sur.

Bug: 1113952
Change-Id: I8280ef793f6da3fe6e85ba9d23a7d5e8188f2371
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342573Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795976}

content/browser/sandbox_mac_unittest.mm

@@ -256,4 +256,26 @@ TEST_F(SandboxMacTest, FontLoadingTest) {
   ASSERT_TRUE(base::DeleteFile(temp_file_path));
 }
 
+MULTIPROCESS_TEST_MAIN(BuiltinAvailable) {
+  CheckCreateSeatbeltServer();
+
+  if (__builtin_available(macOS 10.10, *)) {
+    // Can't negate a __builtin_available condition. But success!
+  } else {
+    return 10;
+  }
+
+  if (__builtin_available(macOS 10.13, *)) {
+    // Can't negate a __builtin_available condition. But success!
+  } else {
+    return 13;
+  }
+
+  return 0;
+}
+
+TEST_F(SandboxMacTest, BuiltinAvailable) {
+  ExecuteInAllSandboxTypes("BuiltinAvailable", {});
+}
+
 }  // namespace content

sandbox/policy/mac/common.sb

@@ -158,6 +158,7 @@
 ; Reads from /System.
 (allow file-read-data
   (path "/System/Library/CoreServices/SystemVersion.plist")
+  (path "/System/Library/CoreServices/SystemVersionCompat.plist") ; https://crbug.com/1108832
   (path "/System/Library/CoreServices/checkfixlist")
 )