Make accelerators not to work when the keyboard overlay is shown.

ash/keyboard_overlay/keyboard_overlay_view.h

Index: ash/keyboard_overlay/keyboard_overlay_view.h
diff --git a/ash/keyboard_overlay/keyboard_overlay_view.h b/ash/keyboard_overlay/keyboard_overlay_view.h
index a0b44e06eae98f60757f1d33f00071183fa0ccdf..c78944ad40cb6fbb90fda29ca1254805c56075c1 100644
--- a/ash/keyboard_overlay/keyboard_overlay_view.h
+++ b/ash/keyboard_overlay/keyboard_overlay_view.h
@@ -6,6 +6,7 @@
 #define ASH_KEYBOARD_OVERLAY_KEYBOARD_OVERLAY_VIEW_H_
 
 #include "ash/ash_export.h"
+#include "ash/wm/overlay_event_filter.h"
 #include "base/compiler_specific.h"
 #include "ui/views/controls/webview/web_dialog_view.h"
 
@@ -20,13 +21,20 @@ class WebDialogDelegate;
 }
 
 // A customized dialog view for the keyboard overlay.
-class ASH_EXPORT KeyboardOverlayView : public views::WebDialogView {
+class ASH_EXPORT KeyboardOverlayView
+    : public views::WebDialogView,
+      public ash::internal::OverlayEventFilter::Delegate {
  public:
   KeyboardOverlayView(content::BrowserContext* context,
                       ui::WebDialogDelegate* delegate,
                       WebContentsHandler* handler);
   virtual ~KeyboardOverlayView();
 
+  // Overridden from ash::internal::OverlayEventFilter::Delegate:
+  virtual void Cancel() OVERRIDE;
+  virtual bool IsCancelKeyEvent(aura::KeyEvent* event) OVERRIDE;
+  virtual aura::Window* GetWindow() OVERRIDE;
+
   // Shows the keyboard overlay.
   static void ShowDialog(content::BrowserContext* context,
                          WebContentsHandler* handler,