[Refactor] Move the logic to update bounds for show type from WorkspaceLayoutManager to DefaultState

ash/wm/window_state_observer.h

Index: ash/wm/window_state_observer.h
diff --git a/ash/wm/window_state_observer.h b/ash/wm/window_state_observer.h
index f177d5fbeba817fdc69f8d2b0e5c411680a6c029..d76b902f72f7a9e594609a0348e42bf479c6472f 100644
--- a/ash/wm/window_state_observer.h
+++ b/ash/wm/window_state_observer.h
@@ -14,12 +14,23 @@ class WindowState;
 
 class ASH_EXPORT WindowStateObserver {
  public:
-  // Called when the window's show type has changed. This is different from
-  // kWindowShowStatekey property change as this will be invoked when the window
+  // Following observer methods are different from kWindowShowStatekey
+  // property change as this will be invoked when the window
   // gets left/right maximized, and auto positioned. |old_type| is the value
   // before the change.
-  virtual void OnWindowShowTypeChanged(WindowState* window_state,
-                                       WindowShowType old_type) {}
+
+  // Called after the window's show type is set to new type, but before
+  // the window's bounds has been updated for the new type.
+  // This is used to update the shell state such as work area so
+  // that the window can use the correct environment to update its bounds.
+  virtual void OnPreWindowShowTypeChange(WindowState* window_state,
+                                         WindowShowType old_type) {}
+
+  // Called after the window's state has been changed for the new show type.
+  // This is used to update the shell state that depends on the update
+  // window bounds, such as shelf visibility.
+  virtual void OnPostWindowShowTypeChange(WindowState* window_state,
+                                          WindowShowType old_type) {}
 };
 
 }  // namespace wm