MacViews: Put wm window animation calls behind an interface.

ui/views/widget/native_widget_aura.cc

Index: ui/views/widget/native_widget_aura.cc
diff --git a/ui/views/widget/native_widget_aura.cc b/ui/views/widget/native_widget_aura.cc
index ea164fb52acf2eb0f8883fb5addccf842bf2891d..0a5778cd6d6dd746de1e4856983d444c3b7f2a5b 100644
--- a/ui/views/widget/native_widget_aura.cc
+++ b/ui/views/widget/native_widget_aura.cc
@@ -36,6 +36,7 @@
 #include "ui/views/widget/widget_aura_utils.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/widget/window_reorderer.h"
+#include "ui/views/widget/window_visibility_animation_aura.h"
 #include "ui/wm/core/shadow_types.h"
 #include "ui/wm/core/window_util.h"
 #include "ui/wm/public/activation_client.h"
@@ -79,6 +80,7 @@ NativeWidgetAura::NativeWidgetAura(internal::NativeWidgetDelegate* delegate)
       destroying_(false),
       cursor_(gfx::kNullCursor),
       saved_window_state_(ui::SHOW_STATE_DEFAULT),
+      visibility_animation_(new WindowVisibilityAnimationAura(window_)),
       close_widget_factory_(this) {
   aura::client::SetFocusChangeObserver(window_, this);
   aura::client::SetActivationChangeObserver(window_, this);
@@ -678,6 +680,10 @@ void NativeWidgetAura::SetVisibilityChangedAnimationsEnabled(bool value) {
     window_->SetProperty(aura::client::kAnimationsDisabledKey, !value);
 }
 
+Widget::VisibilityAnimation* NativeWidgetAura::GetVisibilityAnimation() const {
+  return visibility_animation_.get();
+}
+
 ui::NativeTheme* NativeWidgetAura::GetNativeTheme() const {
 #if !defined(OS_CHROMEOS)
   return DesktopWindowTreeHost::GetNativeTheme(window_);