Adds the message "This is not a crash" to the non-fatal error messages.

This is useful when for investigations that are not a real crash.

Bug: 412867399
Change-Id: I874e93801dd7dc2527080b0cfc468b3eb245241e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6587921
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Wenyu Fu <wenyufu@chromium.org>
Auto-Submit: Wenyu Fu <wenyufu@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1465602}