ui: Cleanup class/struct forward declarations

ash/aura/wm_window_aura.h

Index: ash/aura/wm_window_aura.h
diff --git a/ash/aura/wm_window_aura.h b/ash/aura/wm_window_aura.h
index 9bc3699dd5cb56355d5d9555c1b075649d935702..503a60e2fa02eb6aa88cc8701b7eb58c7ad9e8e8 100644
--- a/ash/aura/wm_window_aura.h
+++ b/ash/aura/wm_window_aura.h
@@ -88,11 +88,6 @@ class ASH_EXPORT WmWindowAura : public WmWindow,
   void SetColorProperty(WmWindowProperty key, SkColor value) override;
   int GetIntProperty(WmWindowProperty key) override;
   void SetIntProperty(WmWindowProperty key, int value) override;
-  std::string GetStringProperty(WmWindowProperty key) override;
-  void SetStringProperty(WmWindowProperty key,
-                         const std::string& value) override;
-  gfx::ImageSkia GetWindowIcon() override;
-  gfx::ImageSkia GetAppIcon() override;
   const wm::WindowState* GetWindowState() const override;
   WmWindow* GetToplevelWindow() override;
   WmWindow* GetToplevelWindowForFocus() override;
@@ -103,7 +98,6 @@ class ASH_EXPORT WmWindowAura : public WmWindow,
   const WmWindow* GetParent() const override;
   const WmWindow* GetTransientParent() const override;
   std::vector<WmWindow*> GetTransientChildren() override;
-  bool MoveToEventRoot(const ui::Event& event) override;
   void SetLayoutManager(
       std::unique_ptr<WmLayoutManager> layout_manager) override;
   WmLayoutManager* GetLayoutManager() override;