[iOS] Adding detail text in -[SettingsSwitchCell accessibilityLabel]

Bug: 919040
Change-Id: I47e6303a2fadb5e587fa7cfbf362495931ee3328
Reviewed-on: https://chromium-review.googlesource.com/c/1396137Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619924}

ios/chrome/browser/ui/settings/cells/settings_switch_cell.mm

@@ -243,7 +243,10 @@ const CGFloat kIconImageSize = 28;
 }
 
 - (NSString*)accessibilityLabel {
-  return _textLabel.text;
+  if (!self.detailTextLabel.text)
+    return self.textLabel.text;
+  return [NSString stringWithFormat:@"%@, %@", self.textLabel.text,
+                                    self.detailTextLabel.text];
 }
 
 - (NSString*)accessibilityValue {