'Continue as' button should be truncated at the end.

ios/chrome/browser/ui/authentication/signin_promo_view.mm

Index: ios/chrome/browser/ui/authentication/signin_promo_view.mm
diff --git a/ios/chrome/browser/ui/authentication/signin_promo_view.mm b/ios/chrome/browser/ui/authentication/signin_promo_view.mm
index 3708677655bb4a56a9afeda005ec75e1d8c42579..bab01cc0082bcd2352838d12851d0aa55fb56ac5 100644
--- a/ios/chrome/browser/ui/authentication/signin_promo_view.mm
+++ b/ios/chrome/browser/ui/authentication/signin_promo_view.mm
@@ -61,6 +61,7 @@ const CGFloat kButtonHeight = 36;
     _primaryButton = [[MDCFlatButton alloc] init];
     _primaryButton.translatesAutoresizingMaskIntoConstraints = NO;
     _primaryButton.accessibilityIdentifier = @"signin_promo_primary_button";
+    _primaryButton.titleLabel.lineBreakMode = NSLineBreakByTruncatingTail;
     [_primaryButton addTarget:self
                        action:@selector(onPrimaryButtonAction:)
              forControlEvents:UIControlEventTouchUpInside];