Ports SystemModalContainerLayoutManager to ash/common

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 7850f84321efe5faaeaedc6e753b869b6142ed93..00ac9ada5f2b5bd9f7386dd12d2f3a424533005f 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -71,6 +71,7 @@ class WindowResizer;
 class WindowSelectorController;
 class WmActivationObserver;
 class WmDisplayObserver;
+class WmRootWindowController;
 class WmWindow;
 class WorkspaceEventHandler;
 
@@ -174,6 +175,9 @@ class ASH_EXPORT WmShell {
 
   virtual WmWindow* GetCaptureWindow() = 0;
 
+  // Convenience for GetPrimaryRootWindow()->GetRootWindowController().
+  WmRootWindowController* GetPrimaryRootWindowController();
+
   virtual WmWindow* GetPrimaryRootWindow() = 0;
 
   // Returns the root window for the specified display.
@@ -215,6 +219,14 @@ class ASH_EXPORT WmShell {
   // Returns true if a system-modal dialog window is currently open.
   bool IsSystemModalWindowOpen();
 
+  // Creates a modal background (a partially-opaque fullscreen window) on all
+  // displays for |window|.
+  void CreateModalBackground(WmWindow* window);
+
+  // Called when a modal window is removed. It will activate another modal
+  // window if any, or remove modal screens on all displays.
+  void OnModalWindowRemoved(WmWindow* removed);
+
   // For testing only: set simulation that a modal window is open
   void SimulateModalWindowOpenForTesting(bool modal_window_open) {
     simulate_modal_window_open_for_testing_ = modal_window_open;