Use light images in colored app frames, when the frame color is dark.

apps/ui/views/app_window_frame_view.h

Index: apps/ui/views/app_window_frame_view.h
diff --git a/apps/ui/views/app_window_frame_view.h b/apps/ui/views/app_window_frame_view.h
index a0fa71dcb08d37b17497c849de23c36c7d1afc95..f29046fb65ef3a6f7111e524a14254737389b3d3 100644
--- a/apps/ui/views/app_window_frame_view.h
+++ b/apps/ui/views/app_window_frame_view.h
@@ -88,6 +88,13 @@ class AppWindowFrameView : public views::NonClientFrameView,
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) OVERRIDE;
 
+  // Some button images we use depend on the color of the frame. This
+  // will set these images based on the color of the frame.
+  void SetButtonImagesForFrame();
+
+  // Return the current frame color based on the active state of the window.
+  SkColor CurrentFrameColor();
+
   views::Widget* widget_;
   NativeAppWindow* window_;
   bool draw_frame_;