Enable DCHECKs by default in non-official builds.

ios/web/web_state/ui/wk_web_view_configuration_provider.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/web/web_state/ui/wk_web_view_configuration_provider.h"
 
 #import <Foundation/Foundation.h>
 #import <WebKit/WebKit.h>
 
 #import "base/ios/weak_nsobject.h"
@@ skipping 69 matching lines @@
     WKUserContentController* userContentController =
         [GetWebViewConfiguration() userContentController];
     router_.reset([[CRWWKScriptMessageRouter alloc]
         initWithUserContentController:userContentController]);
   }
   return router_;
 }
 
 void WKWebViewConfigurationProvider::Purge() {
   DCHECK([NSThread isMainThread]);
-#if !defined(NDEBUG) || !defined(DCHECK_ALWAYS_ON)  // Matches DCHECK_IS_ON.
+#if DCHECK_IS_ON()
   base::WeakNSObject<id> weak_configuration(configuration_);
   base::WeakNSObject<id> weak_router(router_);
   base::WeakNSObject<id> weak_process_pool([configuration_ processPool]);
-#endif  // !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+#endif  // DCHECK_IS_ON()
   configuration_.reset();
   router_.reset();
   // Make sure that no one retains configuration, router, processPool.
+#if DCHECK_IS_ON()
   DCHECK(!weak_configuration);
   DCHECK(!weak_router);
   // TODO(crbug.com/522672): Enable this DCHECK.
   // DCHECK(!weak_process_pool);
+#endif  // DCHECK_IS_ON()
 }
 
 }  // namespace web