Fix typo in documentation.

Change-Id: Ie80bd509889ce66372bd95b59cf75a9b7571723a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1697251
Auto-Submit: Rayan Kanso <rayankans@chromium.org>
Commit-Queue: Varun Khaneja <vakh@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676529}

docs/security/mojo.md

@@ -498,7 +498,7 @@ if (!CheckMul(request->elements(), request->element_size())
          .AssignIfValid(&alloc_size)) {
   // Safe: avoids allocating with a bogus size that overflowed to a smaller than
   // expected value.
-  mojo::ReportBadMessge("Invalid allocation size");
+  mojo::ReportBadMessage("Invalid allocation size");
 }
 
 Element* array = CreateArray(alloc_size);