Move enable extensions define to a build flag.

chrome/browser/profiles/profile_io_data.h

Index: chrome/browser/profiles/profile_io_data.h
diff --git a/chrome/browser/profiles/profile_io_data.h b/chrome/browser/profiles/profile_io_data.h
index 33e601110bfa689928c91619d20e22d1bc33f7ba..016ed498e4a592a3a024a00f76f41938258e1f52 100644
--- a/chrome/browser/profiles/profile_io_data.h
+++ b/chrome/browser/profiles/profile_io_data.h
@@ -30,6 +30,7 @@
 #include "components/prefs/pref_member.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/resource_context.h"
+#include "extensions/features/features.h"
 #include "net/cookies/cookie_monster.h"
 #include "net/http/http_cache.h"
 #include "net/http/http_network_session.h"
@@ -319,7 +320,7 @@ class ProfileIOData {
     scoped_refptr<HostContentSettingsMap> host_content_settings_map;
     scoped_refptr<net::SSLConfigService> ssl_config_service;
     scoped_refptr<net::CookieMonsterDelegate> cookie_monster_delegate;
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
     scoped_refptr<extensions::InfoMap> extension_info_map;
 #endif
     std::unique_ptr<chrome_browser_net::ResourcePrefetchPredictorObserver>
@@ -561,7 +562,7 @@ class ProfileIOData {
   mutable std::unique_ptr<policy::PolicyHeaderIOHelper> policy_header_helper_;
 
   // Pointed to by URLRequestContext.
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   mutable scoped_refptr<extensions::InfoMap> extension_info_map_;
 #endif
 
@@ -620,7 +621,7 @@ class ProfileIOData {
       supervised_user_url_filter_;
 #endif
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   // Is NULL if switches::kDisableExtensionsHttpThrottling is on.
   mutable std::unique_ptr<extensions::ExtensionThrottleManager>
       extension_throttle_manager_;