MacViews: Consolidate flags. Just use --secondary-ui-md to enable MacViews.

chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/chooser_controller/chooser_controller.h"
 #include "chrome/browser/extensions/chrome_extension_chooser_dialog.h"
-#include "chrome/browser/ui/browser_dialogs.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_window.h"
 #import "chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa_controller.h"
 #include "components/web_modal/web_contents_modal_dialog_manager.h"
+#include "ui/base/material_design/material_design_controller.h"
 
 ChooserDialogCocoa::ChooserDialogCocoa(
     content::WebContents* web_contents,
     std::unique_ptr<ChooserController> chooser_controller)
     : web_contents_(web_contents) {
   DCHECK(web_contents_);
   DCHECK(chooser_controller);
   chooser_dialog_cocoa_controller_.reset([[ChooserDialogCocoaController alloc]
       initWithChooserDialogCocoa:this
                chooserController:std::move(chooser_controller)]);
@@ skipping 16 matching lines @@
       CreateAndShowWebModalDialogMac(this, web_contents_, sheet);
 }
 
 void ChooserDialogCocoa::Dismissed() {
   if (constrained_window_)
     constrained_window_->CloseWebContentsModalDialog();
 }
 
 void ChromeExtensionChooserDialog::ShowDialog(
     std::unique_ptr<ChooserController> chooser_controller) const {
-  if (chrome::ToolkitViewsWebUIDialogsEnabled())
+  if (ui::MaterialDesignController::IsSecondaryUiMaterial()) {
     return ChromeExtensionChooserDialog::ShowDialogImpl(
         std::move(chooser_controller));
+  }
 
   web_modal::WebContentsModalDialogManager* manager =
       web_modal::WebContentsModalDialogManager::FromWebContents(web_contents_);
   if (manager) {
     // These objects will delete themselves when the dialog closes.
     ChooserDialogCocoa* chooser_dialog =
         new ChooserDialogCocoa(web_contents_, std::move(chooser_controller));
     chooser_dialog->ShowDialog();
   }
 }