[MD User Menu] Adjusted its background color

ui/native_theme/native_theme_win.cc

 // 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.
 
 #include "ui/native_theme/native_theme_win.h"
 
 #include <windows.h>
 #include <stddef.h>
 #include <uxtheme.h>
 #include <vsstyle.h>
@@ skipping 475 matching lines @@
   const SkColor kResultsTableSelectedUrlColor = SK_ColorWHITE;
 
   switch (color_id) {
     // Windows
     case kColorId_WindowBackground:
       return system_colors_[COLOR_WINDOW];
 
     // Dialogs
     case kColorId_DialogBackground:
     case kColorId_BubbleBackground:
+      if (ui::MaterialDesignController::IsSecondaryUiMaterial())
+        break;
       return color_utils::IsInvertedColorScheme() ?
           color_utils::InvertColor(kDialogBackgroundColor) :
           kDialogBackgroundColor;
 
     // FocusableBorder
     case kColorId_FocusedBorderColor:
       return kFocusedBorderColor;
     case kColorId_UnfocusedBorderColor:
       return kUnfocusedBorderColor;
 
@@ skipping 1554 matching lines @@
     break;
   case LAST:
     NOTREACHED();
     break;
   }
   theme_handles_[theme_name] = handle;
   return handle;
 }
 
 }  // namespace ui