[ash-md] Erases the pre-MD code path for Overview Mode

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 f6aee5e3b040b812b22ec38fc0b84d414da7ff40..518948921b22ca60a3c866a19c8b3e628ed2efe0 100644
--- a/ash/common/wm/overview/scoped_transform_overview_window.h
+++ b/ash/common/wm/overview/scoped_transform_overview_window.h
@@ -92,12 +92,11 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
   gfx::Rect GetTargetBoundsInScreen() const;
 
   // Calculates the bounds of a |window_| after being transformed to the
-  // selector's space. With Material Design those bounds are a union of all
-  // regular (normal and panel) windows in the |window_|'s transient hierarchy.
-  // The returned Rect is in virtual screen coordinates. When |hide_header| is
-  // true the returned bounds are adjusted to allow the original |window_|'s
-  // header to be hidden.
-  gfx::Rect GetTransformedBounds(bool hide_header) const;
+  // selector's space. Those bounds are a union of all regular (normal and
+  // panel) windows in the |window_|'s transient hierarchy. The returned Rect is
+  // in virtual screen coordinates. The returned bounds are adjusted to allow
+  // the original |window_|'s header to be hidden.
+  gfx::Rect GetTransformedBounds() const;
 
   // Returns TOP_VIEW_COLOR property of |window_| unless there are transient
   // ancestors in which case returns SK_ColorTRANSPARENT.
@@ -123,18 +122,14 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
 
   // Applies the |transform| to the overview window and all of its transient
   // children.
-  void SetTransform(WmWindow* root_window,
-                    const gfx::Transform& transform,
-                    bool use_mask);
+  void SetTransform(WmWindow* root_window, const gfx::Transform& transform);
 
   // Set's the opacity of the managed windows.
   void SetOpacity(float opacity);
 
   // Creates a mask layer with the bottom edge 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.
-  void HideHeaderAndSetShape(bool use_mask, bool use_shape, int radius);
+  // |radius|. Uses SetAlphaShape to mask the header.
+  void HideHeaderAndSetShape(int radius);
 
   // Restores original window shape and removes the mask if installed. Safe to
   // call even if HideHeaderAndSetShape() has not been called.
@@ -166,9 +161,6 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
   // A weak pointer to the real window in the overview.
   WmWindow* window_;
 
-  // Mask layer that hides the original window header.
-  std::unique_ptr<OverviewContentMask> mask_;
-
   // Original window shape, if it was set on a window.
   std::unique_ptr<SkRegion> original_window_shape_;