Fix for Ash shortcuts unexpectedly working in system model dialog

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 2f08927ccab2034a515ff1cb8a4bf41642431dee..dbcc2fd70555503dfd99732569a1f805810146c2 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -214,6 +214,11 @@ class ASH_EXPORT Shell : internal::SystemModalContainerEventFilterDelegate{
   // Returns true if a modal dialog window is currently open.
   bool IsModalWindowOpen() const;
 
+  // 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;
+  }
+
   // Creates a default views::NonClientFrameView for use by windows in the
   // Ash environment.
   views::NonClientFrameView* CreateDefaultNonClientFrameView(
@@ -494,6 +499,9 @@ class ASH_EXPORT Shell : internal::SystemModalContainerEventFilterDelegate{
   // Used by ash/shell.
   content::BrowserContext* browser_context_;
 
+  // For testing only: simulate that a modal window is open
+  bool simulate_modal_window_open_for_testing_;
+
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };