Move enable extensions define to a build flag.

chrome/browser/profiles/profile.cc

Index: chrome/browser/profiles/profile.cc
diff --git a/chrome/browser/profiles/profile.cc b/chrome/browser/profiles/profile.cc
index 281e922c1c647638c05708f343058c321806a74e..e7979cce92c2227146c1d6c64c75f79284704988 100644
--- a/chrome/browser/profiles/profile.cc
+++ b/chrome/browser/profiles/profile.cc
@@ -25,6 +25,7 @@
 #include "content/public/browser/storage_partition.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
+#include "extensions/features/features.h"
 
 #if defined(OS_CHROMEOS)
 #include "base/command_line.h"
@@ -32,7 +33,7 @@
 #include "chromeos/chromeos_switches.h"
 #endif
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "extensions/browser/pref_names.h"
 #endif
 
@@ -110,7 +111,7 @@ void Profile::RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
   // TODO(skare): Remove or rename ENABLE_GOOGLE_NOW: http://crbug.com/459827.
   registry->RegisterBooleanPref(prefs::kGoogleNowLauncherEnabled, true);
   registry->RegisterBooleanPref(prefs::kDisableExtensions, false);
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   registry->RegisterBooleanPref(extensions::pref_names::kAlertsInitialized,
                                 false);
 #endif