Replace kIgnoreSoloWindowFramePointerPolicy with global flag

ash/wm/frame_painter.h

Index: ash/wm/frame_painter.h
diff --git a/ash/wm/frame_painter.h b/ash/wm/frame_painter.h
index 1f41c8ce333973c45d6da37db2dcdf2a33967e0f..4a9e9684b5e9662ab4e45ec8817c120af178405c 100644
--- a/ash/wm/frame_painter.h
+++ b/ash/wm/frame_painter.h
@@ -72,6 +72,9 @@ class ASH_EXPORT FramePainter : public aura::WindowObserver,
             views::View* window_icon,
             FrameCaptionButtonContainerView* caption_button_container);
 
+  // Enable/Disable the solo-window transparent header appearance feature.
+  static void SetSoloWindowHeadersEnabled(bool enabled);
+
   // Updates the solo-window transparent header appearance for all windows
   // using frame painters in |root_window|.
   static void UpdateSoloWindowHeader(aura::RootWindow* root_window);