ifdef various extensions code to be used only when extensions are enabled.

chrome/browser/autocomplete/autocomplete_classifier_factory.cc

Index: chrome/browser/autocomplete/autocomplete_classifier_factory.cc
diff --git a/chrome/browser/autocomplete/autocomplete_classifier_factory.cc b/chrome/browser/autocomplete/autocomplete_classifier_factory.cc
index aae29a74561e7f2fcbb34926cbf29cadd8647d85..4fb033678a0424a2971937ca86133a79cb847ecc 100644
--- a/chrome/browser/autocomplete/autocomplete_classifier_factory.cc
+++ b/chrome/browser/autocomplete/autocomplete_classifier_factory.cc
@@ -12,8 +12,11 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
+
+#if defined(ENABLE_EXTENSIONS)
 #include "extensions/browser/extension_system_provider.h"
 #include "extensions/browser/extensions_browser_client.h"
+#endif
 
 // static
 AutocompleteClassifier* AutocompleteClassifierFactory::GetForProfile(
@@ -43,8 +46,10 @@ AutocompleteClassifierFactory::AutocompleteClassifierFactory()
     : BrowserContextKeyedServiceFactory(
         "AutocompleteClassifier",
         BrowserContextDependencyManager::GetInstance()) {
+#if defined(ENABLE_EXTENSIONS)
   DependsOn(
       extensions::ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
+#endif
   DependsOn(TemplateURLServiceFactory::GetInstance());
   // TODO(pkasting): Uncomment these once they exist.
   //   DependsOn(PrefServiceFactory::GetInstance());