Disabling flaky OverridableProceed test.

ios/chrome/browser/ssl/ios_ssl_error_handler_unittest.mm

Index: ios/chrome/browser/ssl/ios_ssl_error_handler_unittest.mm
diff --git a/ios/chrome/browser/ssl/ios_ssl_error_handler_unittest.mm b/ios/chrome/browser/ssl/ios_ssl_error_handler_unittest.mm
index 013d8ad9e4adce6c8be8cfd9417b63d698126efa..1e424fb3d6ce7858f74fb74cde66ac22e4847f0a 100644
--- a/ios/chrome/browser/ssl/ios_ssl_error_handler_unittest.mm
+++ b/ios/chrome/browser/ssl/ios_ssl_error_handler_unittest.mm
@@ -67,7 +67,8 @@ TEST_F(IOSSSLErrorHandlerTest, NonOverridable) {
 }
 
 // Tests proceed with overridable error.
-TEST_F(IOSSSLErrorHandlerTest, OverridableProceed) {
+// Flaky: http://crbug.com/660343.
+TEST_F(IOSSSLErrorHandlerTest, DISABLED_OverridableProceed) {
   net::SSLInfo ssl_info;
   ssl_info.cert = cert();
   GURL url(kTestHostName);