Add window overview mode behind --ash-enable-overview-mode flag to F5 key.

ash/wm/window_animations.h

Index: ash/wm/window_animations.h
diff --git a/ash/wm/window_animations.h b/ash/wm/window_animations.h
index d56f2b2f40f1d1ca9f0a898c90de25f50019b117..d6f15bee331af3e379ff3331dad43e8f91e5694e 100644
--- a/ash/wm/window_animations.h
+++ b/ash/wm/window_animations.h
@@ -37,6 +37,9 @@ enum LayerScaleAnimationDirection {
   LAYER_SCALE_ANIMATION_BELOW,
 };
 
+// Returns the bounds that |window| should animate to when minimizing.
+ASH_EXPORT gfx::Rect GetMinimizeRectForWindow(aura::Window* window);
+
 // Animate a cross-fade of |window| from its current bounds to |new_bounds|.
 ASH_EXPORT void CrossFadeToBounds(aura::Window* window,
                                   const gfx::Rect& new_bounds);