Don't dismiss Settings when another view controller is presented on top

ios/chrome/browser/ui/settings/settings_navigation_controller.mm

Index: ios/chrome/browser/ui/settings/settings_navigation_controller.mm
diff --git a/ios/chrome/browser/ui/settings/settings_navigation_controller.mm b/ios/chrome/browser/ui/settings/settings_navigation_controller.mm
index e80c01d0d865533a44c393f80afad932a66ff53c..9cd26a2e3a2d264e574b569ba40c800919d61a15 100644
--- a/ios/chrome/browser/ui/settings/settings_navigation_controller.mm
+++ b/ios/chrome/browser/ui/settings/settings_navigation_controller.mm
@@ -542,6 +542,9 @@ initWithRootViewController:(UIViewController*)rootViewController
 #pragma mark - UIResponder
 
 - (NSArray*)keyCommands {
+  if ([self presentedViewController]) {

[gambard, 2017/02/24 12:33:28]

Are you sure this is reset to nil when the presented view controller is
dismissed?
Maybe we should add an EG test?

[lpromero, 2017/02/27 16:55:52]

Done. (Yes the property is correctly updated.)

+    return nil;
+  }
   base::WeakNSObject<SettingsNavigationController> weakSelf(self);
   return @[
     [UIKeyCommand cr_keyCommandWithInput:UIKeyInputEscape