Do not use assets for Ash window control button backgrounds

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

Index: chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
diff --git a/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc b/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
index ce101084edd5d418afce03a2b9e09177bd1c9aca..55166baf6f21430caa7cae592bdc5e537d61bc9d 100644
--- a/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
+++ b/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
@@ -176,8 +176,17 @@ int BrowserNonClientFrameViewAsh::GetTopInset(bool restored) const {
     return 0;
 
   if (browser_view()->IsTabStripVisible()) {
-    return ((frame()->IsMaximized() || frame()->IsFullscreen()) && !restored) ?
-        kTabstripTopSpacingShort : kTabstripTopSpacingTall;
+    // 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();
+    } else {
+      return ((frame()->IsMaximized() ||
+              frame()->IsFullscreen()) &&
+              !restored) ? kTabstripTopSpacingShort : kTabstripTopSpacingTall;
+    }
   }
 
   if (UsePackagedAppHeaderStyle() || UseWebAppHeaderStyle())