cocoa browser: remove non-material toolbar support

chrome/browser/ui/cocoa/toolbar/app_toolbar_button.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/toolbar/app_toolbar_button.h"
 
 #include "base/macros.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
 #include "ui/base/material_design/material_design_controller.h"
@@ skipping 34 matching lines @@
 }
 
 - (void)commonInit {
   view_id_util::SetID(self, VIEW_ID_APP_MENU);
   delegate_.reset(new AppMenuButtonIconPainterDelegateMac(self));
   severity_ = AppMenuIconPainter::Severity::SEVERITY_NONE;
   type_ = AppMenuIconController::IconType::NONE;
 }
 
 - (gfx::VectorIconId)vectorIconId {
-  CHECK(ui::MaterialDesignController::IsModeMaterial());
   switch (type_) {
     case AppMenuIconController::IconType::NONE:
       DCHECK_EQ(severity_, AppMenuIconPainter::SEVERITY_NONE);
       return gfx::VectorIconId::BROWSER_TOOLS;
     case AppMenuIconController::IconType::UPGRADE_NOTIFICATION:
       return gfx::VectorIconId::BROWSER_TOOLS_UPDATE;
     case AppMenuIconController::IconType::GLOBAL_ERROR:
     case AppMenuIconController::IconType::INCOMPATIBILITY_WARNING:
       return gfx::VectorIconId::BROWSER_TOOLS_ERROR;
   }
@@ skipping 29 matching lines @@
       shouldAnimate:(BOOL)shouldAnimate {
   if (severity != severity_ || type != type_) {
     severity_ = severity;
     type_ = type;
     // Update the button state images with the new severity color or icon type.
     [self resetButtonStateImages];
   }
 }
 
 @end