Revert of Enable DCHECKs by default in non-official builds.

ios/web/web_state/ui/wk_web_view_configuration_provider.mm

Index: ios/web/web_state/ui/wk_web_view_configuration_provider.mm
diff --git a/ios/web/web_state/ui/wk_web_view_configuration_provider.mm b/ios/web/web_state/ui/wk_web_view_configuration_provider.mm
index 7527133963eaf71a5d883e8b9da24a8d72e6df5a..e3386c5b0ad89d12ccc5f5c55095f40c906879fe 100644
--- a/ios/web/web_state/ui/wk_web_view_configuration_provider.mm
+++ b/ios/web/web_state/ui/wk_web_view_configuration_provider.mm
@@ -87,20 +87,18 @@
 
 void WKWebViewConfigurationProvider::Purge() {
   DCHECK([NSThread isMainThread]);
-#if DCHECK_IS_ON()
+#if !defined(NDEBUG) || !defined(DCHECK_ALWAYS_ON)  // Matches DCHECK_IS_ON.
   base::WeakNSObject<id> weak_configuration(configuration_);
   base::WeakNSObject<id> weak_router(router_);
   base::WeakNSObject<id> weak_process_pool([configuration_ processPool]);
-#endif  // DCHECK_IS_ON()
+#endif  // !defined(NDEBUG) || defined(DCHECK_ALWAYS_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