Moves maintaining root_window_for_new_windows_ to Shell

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index f17b9a7ff4f43451afc62a32461332619be0d26f..e105ab51ba0cc60cd26e7d9e24bc736c738fd0fb 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -22,6 +22,7 @@
 #include "ui/display/screen.h"
 #include "ui/events/event_target.h"
 #include "ui/wm/core/cursor_manager.h"
+#include "ui/wm/public/activation_change_observer.h"
 
 namespace aura {
 class RootWindow;
@@ -141,7 +142,8 @@ class SmsObserverTest;
 // Upon creation, the Shell sets itself as the RootWindow's delegate, which
 // takes ownership of the Shell.
 class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
-                         public ui::EventTarget {
+                         public ui::EventTarget,
+                         public aura::client::ActivationChangeObserver {
  public:
   typedef std::vector<RootWindowController*> RootWindowControllerList;
 
@@ -389,6 +391,17 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
     return is_touch_hud_projection_enabled_;
   }
 
+  // NOTE: Prefer ScopedRootWindowForNewWindows when setting temporarily.
+  void set_root_window_for_new_windows(WmWindow* root) {
+    root_window_for_new_windows_ = root;
+  }
+
+  // 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();

[James Cook, 2017/03/08 03:04:16]

Aside: I'm glad you choose this name for the WmWindow implementation. It's much
better than the old "target root window" name.

+
   // Creates instance of FirstRunHelper. Caller is responsible for deleting
   // returned object.
   ash::FirstRunHelper* CreateFirstRunHelper();
@@ -414,9 +427,10 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   FRIEND_TEST_ALL_PREFIXES(WindowManagerTest, MouseEventCursors);
   FRIEND_TEST_ALL_PREFIXES(WindowManagerTest, TransformActivate);
   friend class RootWindowController;
+  friend class ScopedRootWindowForNewWindows;
+  friend class SmsObserverTest;
   friend class test::ShellTestApi;
   friend class shell::WindowWatcher;
-  friend class SmsObserverTest;
 
   explicit Shell(std::unique_ptr<WmShell> wm_shell);
   ~Shell() override;
@@ -441,6 +455,11 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   std::unique_ptr<ui::EventTargetIterator> GetChildIterator() const override;
   ui::EventTargeter* GetEventTargeter() override;
 
+  // aura::client::ActivationChangeObserver:
+  void OnWindowActivated(ActivationReason reason,
+                         aura::Window* gained_active,
+                         aura::Window* lost_active) override;
+
   static Shell* instance_;
 
   // Only valid in mash, for classic ash this is null.
@@ -564,6 +583,10 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
 
   bool is_touch_hud_projection_enabled_;
 
+  // See comment for GetRootWindowForNewWindows().
+  WmWindow* root_window_for_new_windows_ = nullptr;
+  WmWindow* scoped_root_window_for_new_windows_ = nullptr;
+
   // Injected content::GPUDataManager support.
   std::unique_ptr<GPUSupport> gpu_support_;