Updates WKWebViewSecurityUtil to handle deprecated enum values.

ios/web/web_state/wk_web_view_security_util.mm

Index: ios/web/web_state/wk_web_view_security_util.mm
diff --git a/ios/web/web_state/wk_web_view_security_util.mm b/ios/web/web_state/wk_web_view_security_util.mm
index b927e676edfcd85b8896d800a6c88d512afb15ad..5836fab7bedb1e82103805e815a5d325ac121e43 100644
--- a/ios/web/web_state/wk_web_view_security_util.mm
+++ b/ios/web/web_state/wk_web_view_security_util.mm
@@ -139,9 +139,15 @@ SecurityStyle GetSecurityStyleFromTrustResult(SecTrustResultType result) {
     case kSecTrustResultFatalTrustFailure:
     case kSecTrustResultOtherError:
       return SECURITY_STYLE_AUTHENTICATION_BROKEN;
+
+    // TODO(crbug.com/619982): This default clause exists because
+    // kSecTrustResultConfirm was deprecated in iOS7, but leads to a compile
+    // error if used with newer SDKs.  Remove the default clause once this
+    // switch statement successfully compiles without kSecTrustResultConfirm.
+    default:
+      NOTREACHED();
+      return SECURITY_STYLE_UNKNOWN;
   }
-  NOTREACHED();
-  return SECURITY_STYLE_UNKNOWN;
 }
 
 }  // namespace web