Do not use assets for Ash window control button backgrounds

chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc

 // Copyright 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 "chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.h"
 
 #include <algorithm>
 
 #include "ash/frame/caption_buttons/frame_caption_button_container_view.h"
 #include "ash/frame/default_header_painter.h"
@@ skipping 159 matching lines @@
                    GetTopInset(false),
                    std::max(0, width() - left_inset - right_inset),
                    tabstrip->GetPreferredSize().height());
 }
 
 int BrowserNonClientFrameViewAsh::GetTopInset(bool restored) const {
   if (!ShouldPaint() || UseImmersiveLightbarHeaderStyle())
     return 0;
 
   if (browser_view()->IsTabStripVisible()) {
+    // TODO(tdanderson): Remove this temporary hack to prevent the buttons in
+    //                   the header from overlapping the tabstrip/toolbar
+    //                   separator in material design.
+    if (ui::MaterialDesignController::IsModeMaterial()) {
+      return header_painter_->GetHeaderHeight() -
+          browser_view()->GetTabStripHeight();
+    }
+
     return ((frame()->IsMaximized() || frame()->IsFullscreen()) && !restored) ?
         kTabstripTopSpacingShort : kTabstripTopSpacingTall;
   }
 
   if (UsePackagedAppHeaderStyle() || UseWebAppHeaderStyle())
     return header_painter_->GetHeaderHeight();
 
   int caption_buttons_bottom = caption_button_container_->bounds().bottom();
 
   // The toolbar partially overlaps the caption buttons.
@@ skipping 511 matching lines @@
   }
 }
 
 void BrowserNonClientFrameViewAsh::PaintContentEdge(gfx::Canvas* canvas) {
   DCHECK(!UsePackagedAppHeaderStyle() && !UseWebAppHeaderStyle());
   canvas->FillRect(
       gfx::Rect(0, caption_button_container_->bounds().bottom(), width(),
                 kClientEdgeThickness),
       GetThemeProvider()->GetColor(ThemeProperties::COLOR_TOOLBAR_SEPARATOR));
 }