Move enable extensions define to a build flag.

chrome/browser/nacl_host/nacl_browser_delegate_impl.h

Index: chrome/browser/nacl_host/nacl_browser_delegate_impl.h
diff --git a/chrome/browser/nacl_host/nacl_browser_delegate_impl.h b/chrome/browser/nacl_host/nacl_browser_delegate_impl.h
index 5ca7dbbe79265b3959c57fe120502c3961504f79..a968d975ca57a7be848ef7db5c2e3947bd56b2ae 100644
--- a/chrome/browser/nacl_host/nacl_browser_delegate_impl.h
+++ b/chrome/browser/nacl_host/nacl_browser_delegate_impl.h
@@ -11,8 +11,9 @@
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "components/nacl/browser/nacl_browser_delegate.h"
+#include "extensions/features/features.h"
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "base/memory/ref_counted.h"
 #include "extensions/common/url_pattern.h"
 
@@ -50,7 +51,7 @@ class NaClBrowserDelegateImpl : public NaClBrowserDelegate {
                            const GURL& manifest_url) override;
 
  private:
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   scoped_refptr<extensions::InfoMap> GetExtensionInfoMap(
       const base::FilePath& profile_directory);
   std::vector<URLPattern> debug_patterns_;