Split javascript_dialogs.cc into views and cocoa+views versions.

chrome/browser/ui/javascript_dialogs/javascript_dialog_mac.cc

 // Copyright 2016 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.
 
 #include "chrome/browser/ui/javascript_dialogs/javascript_dialog.h"
 
-#include "build/build_config.h"
-#include "chrome/browser/ui/javascript_dialogs/javascript_dialog_views.h"
-
-#if defined(OS_MACOSX)
 #include "chrome/browser/ui/browser_dialogs.h"
 #include "chrome/browser/ui/javascript_dialogs/javascript_dialog_cocoa.h"
-#endif
+#include "chrome/browser/ui/javascript_dialogs/javascript_dialog_views.h"
 
 JavaScriptDialog::~JavaScriptDialog() = default;
 
 base::WeakPtr<JavaScriptDialog> JavaScriptDialog::Create(
     content::WebContents* parent_web_contents,
     content::WebContents* alerting_web_contents,
     const base::string16& title,
     content::JavaScriptMessageType message_type,
     const base::string16& message_text,
     const base::string16& default_prompt_text,
     const content::JavaScriptDialogManager::DialogClosedCallback&
         dialog_callback) {
-#if defined(OS_MACOSX)
   if (chrome::ToolkitViewsWebUIDialogsEnabled()) {
-#endif
     return JavaScriptDialogViews::Create(
         parent_web_contents, alerting_web_contents, title, message_type,
         message_text, default_prompt_text, dialog_callback);
-#if defined(OS_MACOSX)
   } else {
     return JavaScriptDialogCocoa::Create(
         parent_web_contents, alerting_web_contents, title, message_type,
         message_text, default_prompt_text, dialog_callback);
   }
-#endif
 }