Repalced GetInstanceForWebUi() with GetNativeTheme() in glass frame

Bug: 1056916
Change-Id: I473116523113dd420196af63386da02a16ef1015
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2123911Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754541}

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

@@ -179,6 +179,8 @@ int GlassBrowserFrameView::GetThemeBackgroundXInset() const {
 
 bool GlassBrowserFrameView::HasVisibleBackgroundTabShapes(
     BrowserFrameActiveState active_state) const {
+  DCHECK(GetWidget());
+
   // Pre-Win 8, tabs never match the glass frame appearance.
   if (base::win::GetVersion() < base::win::Version::WIN8)
     return true;
@@ -189,7 +191,7 @@ bool GlassBrowserFrameView::HasVisibleBackgroundTabShapes(
   // colors).
   // TODO(pkasting): https://crbug.com/831769  Change the architecture of the
   // high contrast support to respect system colors, then remove this.
-  if (ui::NativeTheme::GetInstanceForNativeUi()->UsesHighContrastColors())
+  if (GetNativeTheme()->UsesHighContrastColors())
     return true;
 
   return BrowserNonClientFrameView::HasVisibleBackgroundTabShapes(active_state);