Support prefix typing in Combobox while menu is open

ui/views/controls/menu/submenu_view.h

Index: ui/views/controls/menu/submenu_view.h
diff --git a/ui/views/controls/menu/submenu_view.h b/ui/views/controls/menu/submenu_view.h
index 57c870e88c6440ceba69cce5cc4f7d434d044232..e5ce541348513977ae5e51833d513ee0498bf25d 100644
--- a/ui/views/controls/menu/submenu_view.h
+++ b/ui/views/controls/menu/submenu_view.h
@@ -10,6 +10,8 @@
 #include "base/compiler_specific.h"
 #include "ui/views/animation/scroll_animator.h"
 #include "ui/views/controls/menu/menu_delegate.h"
+#include "ui/views/controls/prefix_delegate.h"
+#include "ui/views/controls/prefix_selector.h"
 #include "ui/views/view.h"
 
 namespace views {
@@ -33,7 +35,7 @@ class MenuScrollViewContainer;
 // MenuScrollViewContainer handles showing as much of the SubmenuView as the
 // screen allows. If the SubmenuView is taller than the screen, scroll buttons
 // are provided that allow the user to see all the menu items.
-class VIEWS_EXPORT SubmenuView : public View,
+class VIEWS_EXPORT SubmenuView : public PrefixDelegate,
                                  public ScrollDelegate {
  public:
   // The submenu's class name.
@@ -57,6 +59,7 @@ class VIEWS_EXPORT SubmenuView : public View,
 
   // Override from View.
   virtual void GetAccessibleState(ui::AccessibleViewState* state) OVERRIDE;
+  virtual ui::TextInputClient* GetTextInputClient() OVERRIDE;
 
   // Painting.
   virtual void PaintChildren(gfx::Canvas* canvas) OVERRIDE;
@@ -79,6 +82,12 @@ class VIEWS_EXPORT SubmenuView : public View,
   // Scrolls on menu item boundaries.
   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
+  // Overridden from PrefixDelegate.
+  virtual int GetRowCount() OVERRIDE;
+  virtual int GetSelectedRow() OVERRIDE;
+  virtual void SetSelectedRow(int row) OVERRIDE;
+  virtual base::string16 GetTextForRow(int row) OVERRIDE;
+
   // Returns true if the menu is showing.
   bool IsShowing();
 
@@ -208,6 +217,8 @@ class VIEWS_EXPORT SubmenuView : public View,
   // is enabled. See crbug.com/329354.
   float roundoff_error_;
 
+  PrefixSelector prefix_selector_;
+
   DISALLOW_COPY_AND_ASSIGN(SubmenuView);
 };