Test for crash fix

https://crrev.com/c/4335571 fixed a crash with bogus extensions. Add
a test to prevent regressions.

Bug: 1423362
Change-Id: I2e4ac1fa1a48a13be8ceeac80b09093fd251c77b
Fixed: 1426193
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4368782
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Auto-Submit: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1121915}

ui/shell_dialogs/select_file_dialog_mac_unittest.mm

@@ -524,6 +524,18 @@ void ResetDialog() {
   EXPECT_FALSE(panel.extensionHidden);
 }
 
+TEST_F(SelectFileDialogMacTest, DontCrashWithBogusExtension) {
+  SelectFileDialog::FileTypeInfo file_type_info;
+  file_type_info.extensions = {{"bogus type", "j.pg"}};
+
+  FileDialogArguments args;
+  args.file_types = &file_type_info;
+
+  NSSavePanel* panel = SelectFileWithParams(args);
+  // If execution gets this far, there was no crash.
+  EXPECT_TRUE(panel);
+}
+
 // Test to ensure lifetime is sound if a reference to
 // the panel outlives the delegate.
 TEST_F(SelectFileDialogMacTest, Lifetime) {