Engage the presubmit warning for OS_MACOSX

OS_MACOSX will still work for code already in the tree, but warn
to prevent new instances from landing.

Bug: 1105907
Change-Id: Ia811e352ab7ec688bad5e8e7b31868777dd75c10
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2328330
Commit-Queue: Avi Drissman <[email protected]>
Commit-Queue: Dirk Pranke <[email protected]>
Auto-Submit: Avi Drissman <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Cr-Commit-Position: refs/heads/master@{#793021}
diff --git a/PRESUBMIT_test.py b/PRESUBMIT_test.py
index 8286775..111f2b2 100755
--- a/PRESUBMIT_test.py
+++ b/PRESUBMIT_test.py
@@ -275,6 +275,7 @@
     lines = ['#if defined(OS_WINDOWS)',
              ' #elif defined(OS_WINDOW)',
              ' # if defined(OS_MAC) || defined(OS_CHROME)',
+             '# else  // defined(OS_MACOSX)',
              '#endif  // defined(OS_MACOS)']
     errors = PRESUBMIT._CheckForInvalidOSMacrosInFile(
         MockInputApi(), MockFile('some/path/foo_platform.cc', lines))