Move enable extensions define to a build flag.

chrome/browser/chrome_content_browser_client.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "build/build_config.h"
 #include "content/public/browser/content_browser_client.h"
+#include "extensions/features/features.h"
 
 class ChromeContentBrowserClientParts;
 
 namespace base {
 class CommandLine;
 }
 
 namespace content {
 class BrowserContext;
 class QuotaPermissionContext;
@@ skipping 289 matching lines @@
       const base::CommandLine& from_command_line,
       version_info::Channel channel);
 #endif
 
   void FileSystemAccessed(
       const GURL& url,
       const std::vector<std::pair<int, int> >& render_frames,
       base::Callback<void(bool)> callback,
       bool allow);
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   void GuestPermissionRequestHelper(
       const GURL& url,
       const std::vector<std::pair<int, int> >& render_frames,
       base::Callback<void(bool)> callback,
       bool allow);
 
   static void RequestFileSystemPermissionOnUIThread(
       int render_process_id,
       int render_frame_id,
       const GURL& url,
@@ skipping 14 matching lines @@
   // Vector of additional ChromeContentBrowserClientParts.
   // Parts are deleted in the reverse order they are added.
   std::vector<ChromeContentBrowserClientParts*> extra_parts_;
 
   base::WeakPtrFactory<ChromeContentBrowserClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeContentBrowserClient);
 };
 
 #endif  // CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_