Refactor PhantomWindowController so that the PhantomWindowController owns the phantom window

ash/wm/workspace/workspace_window_resizer.cc

Index: ash/wm/workspace/workspace_window_resizer.cc
diff --git a/ash/wm/workspace/workspace_window_resizer.cc b/ash/wm/workspace/workspace_window_resizer.cc
index 9d64fb2bca5a6da4d6a8aad980bbfc33d32c03e9..6a6c73545de4d2608c1cee36bc3782fb484ab51c 100644
--- a/ash/wm/workspace/workspace_window_resizer.cc
+++ b/ash/wm/workspace/workspace_window_resizer.cc
@@ -561,15 +561,6 @@ WorkspaceWindowResizer::WorkspaceWindowResizer(
   instance_ = this;
 }
 
-gfx::Rect WorkspaceWindowResizer::GetFinalBounds(
-    const gfx::Rect& bounds) const {
-  if (snap_phantom_window_controller_.get() &&
-      snap_phantom_window_controller_->IsShowing()) {
-    return snap_phantom_window_controller_->bounds_in_screen();
-  }
-  return bounds;
-}
-
 void WorkspaceWindowResizer::LayoutAttachedWindows(
     gfx::Rect* bounds) {
   gfx::Rect work_area(ScreenAsh::GetDisplayWorkAreaBoundsInParent(window()));