Enable -Wundeclared-selector on ios.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/ui/settings/password_details_collection_view_controller.h"
 
 #import "base/ios/weak_nsobject.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 72 matching lines @@
   if (self) {
     _weakDelegate.reset(delegate);
     _weakReauthenticationModule.reset(reauthenticationModule);
     _passwordForm = passwordForm;
     _username.reset([username copy]);
     _password.reset([password copy]);
     self.title =
         [PasswordDetailsCollectionViewController simplifyOrigin:origin];
     NSNotificationCenter* defaultCenter = [NSNotificationCenter defaultCenter];
     [defaultCenter addObserver:self
-                      selector:@selector(hidePassword:)
+                      selector:@selector(hidePassword)
                           name:UIApplicationDidEnterBackgroundNotification
                         object:nil];
 
     [self loadModel];
   }
   return self;
 }
 
 + (NSString*)simplifyOrigin:(NSString*)origin {
   NSString* originWithoutScheme = nil;
@@ skipping 230 matching lines @@
     case ItemTypePassword:
       return [MDCCollectionViewCell
           cr_preferredHeightForWidth:CGRectGetWidth(collectionView.bounds)
                              forItem:item];
     default:
       return MDCCellDefaultOneLineHeight;
   }
 }
 
 @end