Change name of NativeTheme::instance() to make it clear it's web only.

ui/views/button_drag_utils.cc

Index: ui/views/button_drag_utils.cc
diff --git a/ui/views/button_drag_utils.cc b/ui/views/button_drag_utils.cc
index cca89ea1eb217f05be760057d0ee7f418cd1f55b..3fb5d12ed61b619b3e246cb0727fea3642b1c87c 100644
--- a/ui/views/button_drag_utils.cc
+++ b/ui/views/button_drag_utils.cc
@@ -47,8 +47,7 @@ void SetDragImage(const GURL& url,
                             title.empty() ? base::UTF8ToUTF16(url.spec())
                                           : title);
   button.SetTextSubpixelRenderingEnabled(false);
-  const ui::NativeTheme* theme =
-      widget ? widget->GetNativeTheme() : ui::NativeTheme::instance();

[Evan Stade, 2015/11/19 23:29:14]

I looked at the call sites and I think |widget| is always non null. Exercising
the code (dragging from the location icon or url text) likewise worked fine.

+  const ui::NativeTheme* theme = widget->GetNativeTheme();
   button.SetTextColor(views::Button::STATE_NORMAL,
       theme->GetSystemColor(ui::NativeTheme::kColorId_LabelEnabledColor));
   gfx::ShadowValues shadows(