[ash-md] Fades overview header in and out

ash/common/wm/overview/scoped_transform_overview_window.h

Index: ash/common/wm/overview/scoped_transform_overview_window.h
diff --git a/ash/common/wm/overview/scoped_transform_overview_window.h b/ash/common/wm/overview/scoped_transform_overview_window.h
index 11b50ef1c146b9bc6358793687b1e6085d90749c..2efe6ccc3bdcd1be05c10d480f459aba06daa348 100644
--- a/ash/common/wm/overview/scoped_transform_overview_window.h
+++ b/ash/common/wm/overview/scoped_transform_overview_window.h
@@ -32,6 +32,7 @@ class WmWindow;
 // object.
 class ASH_EXPORT ScopedTransformOverviewWindow {
  public:
+  class OverviewContentMask;
   using ScopedAnimationSettings =
       std::vector<std::unique_ptr<ScopedOverviewAnimationSettings>>;
 
@@ -120,12 +121,14 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
   // using rounded corners of |radius|. When |use_mask| is set, hides the
   // original window header and uses rounded rectangle mask which may be
   // resource-intensive. When |use_shape| is set and |use_mask| is not, uses
-  // SetAlphaShape to mask the header.
+  // SetAlphaShape to mask the header. If |animate| is set, the shape or mask
+  // is set only upon the animation completion.
   void SetTransform(WmWindow* root_window,
                     const gfx::Transform& transform,
                     bool use_mask,
                     bool use_shape,
-                    float radius);
+                    float radius,
+                    bool animate);
 
   // Set's the opacity of the managed windows.
   void SetOpacity(float opacity);
@@ -136,8 +139,8 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
   void Close();
 
  private:
+  class OverviewWindowAnimationObserver;
   friend class WindowSelectorTest;
-  class OverviewContentMask;
 
   enum OriginalVisibility {
     ORIGINALLY_VISIBLE,
@@ -163,6 +166,10 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
   // Original window shape, if it was set on a window.
   std::unique_ptr<SkRegion> original_window_shape_;
 
+  // Observes transform animation and hides the window header when the animation
+  // completes.
+  std::unique_ptr<OverviewWindowAnimationObserver> animation_observer_;
+
   // True after the |original_window_shape_| has been set or after it has
   // been determined that window shape was not originally set on the |window_|.
   bool determined_original_window_shape_;