Moves maintaining root_window_for_new_windows_ to Shell

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index 2adc80dcccb75225fb24e7d9b28f6c13e1e4b299..1a5186297d556308b904acc7a24b391cfffe1fde 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -19,7 +19,6 @@
 #include "components/ui_devtools/devtools_server.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/compositor/layer_type.h"
-#include "ui/wm/public/activation_change_observer.h"
 #include "ui/wm/public/window_types.h"
 
 namespace app_list {
@@ -103,8 +102,7 @@ class WindowState;
 }
 
 // Similar to ash::Shell. Eventually the two will be merged.
-class ASH_EXPORT WmShell : public SessionStateObserver,
-                           public aura::client::ActivationChangeObserver {
+class ASH_EXPORT WmShell : public SessionStateObserver {
  public:
   ~WmShell() override;
 
@@ -163,11 +161,6 @@ class ASH_EXPORT WmShell : public SessionStateObserver,
     return new_window_controller_.get();
   }
 
-  // NOTE: Prefer ScopedRootWindowForNewWindows when setting temporarily.
-  void set_root_window_for_new_windows(WmWindow* root) {
-    root_window_for_new_windows_ = root;
-  }
-
   PaletteDelegate* palette_delegate() { return palette_delegate_.get(); }
 
   preferences::PrefClientStore* pref_store() { return pref_store_.get(); }
@@ -237,12 +230,6 @@ class ASH_EXPORT WmShell : public SessionStateObserver,
   // Returns the root window for the specified display.
   virtual WmWindow* GetRootWindowForDisplayId(int64_t display_id) = 0;
 
-  // Returns the root window that newly created windows should be added to.
-  // Value can be temporarily overridden using ScopedRootWindowForNewWindows.
-  // NOTE: this returns the root, newly created window should be added to the
-  // appropriate container in the returned window.
-  WmWindow* GetRootWindowForNewWindows();
-
   // Retuns the display info associated with |display_id|.
   // TODO(mash): Remove when DisplayManager has been moved. crbug.com/622480
   virtual const display::ManagedDisplayInfo& GetDisplayInfo(
@@ -486,15 +473,9 @@ class ASH_EXPORT WmShell : public SessionStateObserver,
 
  private:
   friend class AcceleratorControllerTest;
-  friend class ScopedRootWindowForNewWindows;
   friend class Shell;
   friend class WmShellTestApi;
 
-  // aura::client::ActivationChangeObserver:
-  void OnWindowActivated(ActivationReason reason,
-                         aura::Window* gained_active,
-                         aura::Window* lost_active) override;
-
   static WmShell* instance_;
 
   base::ObserverList<ShellObserver> shell_observers_;
@@ -537,10 +518,6 @@ class ASH_EXPORT WmShell : public SessionStateObserver,
 
   base::ObserverList<LockStateObserver> lock_state_observers_;
 
-  // See comment for GetRootWindowForNewWindows().
-  WmWindow* root_window_for_new_windows_ = nullptr;
-  WmWindow* scoped_root_window_for_new_windows_ = nullptr;
-
   bool simulate_modal_window_open_for_testing_ = false;
 
   scoped_refptr<base::SequencedWorkerPool> blocking_pool_;