Do not hide shadow underlay for max/fullscreen state even if the client disables the shadow.

components/exo/shell_surface.h

Index: components/exo/shell_surface.h
diff --git a/components/exo/shell_surface.h b/components/exo/shell_surface.h
index c8087ad78d9d15ea89215ebdd08980cdece9cfa4..308a09769cfc703669587eaf738c4df1bc6f39f4 100644
--- a/components/exo/shell_surface.h
+++ b/components/exo/shell_surface.h
@@ -276,8 +276,8 @@ class ShellSurface : public SurfaceDelegate,
   // Overridden from ui::AcceleratorTarget:
   bool AcceleratorPressed(const ui::Accelerator& accelerator) override;
 
-  aura::Window* shadow_overlay() { return shadow_overlay_; }
-  aura::Window* shadow_underlay() { return shadow_underlay_; }
+  aura::Window* shadow_overlay() { return shadow_overlay_.get(); }
+  aura::Window* shadow_underlay() { return shadow_underlay_.get(); }
 
   Surface* surface_for_testing() { return surface_; }
 
@@ -335,6 +335,8 @@ class ShellSurface : public SurfaceDelegate,
   // In the coordinate system of the parent root window.
   gfx::Point GetMouseLocation() const;
 
+  void ResetShadowWindows();
+
   views::Widget* widget_ = nullptr;
   Surface* surface_;
   aura::Window* parent_;
@@ -365,8 +367,8 @@ class ShellSurface : public SurfaceDelegate,
   gfx::Vector2d pending_origin_offset_accumulator_;
   int resize_component_ = HTCAPTION;  // HT constant (see ui/base/hit_test.h)
   int pending_resize_component_ = HTCAPTION;
-  aura::Window* shadow_overlay_ = nullptr;
-  aura::Window* shadow_underlay_ = nullptr;
+  std::unique_ptr<aura::Window> shadow_overlay_;
+  std::unique_ptr<aura::Window> shadow_underlay_;
   std::unique_ptr<ui::EventHandler> shadow_underlay_event_handler_;
   gfx::Rect shadow_content_bounds_;
   float shadow_background_opacity_ = 1.0;