Remove the 2-level input method system & InputMethodBridge.

ui/views/controls/tree/tree_view.h

Index: ui/views/controls/tree/tree_view.h
diff --git a/ui/views/controls/tree/tree_view.h b/ui/views/controls/tree/tree_view.h
index 0cb3760333765806efd07860dd0da01d7d02de74..fdcff6727359982b5592b83558506b9f8c80fd42 100644
--- a/ui/views/controls/tree/tree_view.h
+++ b/ui/views/controls/tree/tree_view.h
@@ -124,7 +124,6 @@ class VIEWS_EXPORT TreeView : public ui::TreeModelObserver,
   gfx::Size GetPreferredSize() const override;
   bool AcceleratorPressed(const ui::Accelerator& accelerator) override;
   bool OnMousePressed(const ui::MouseEvent& event) override;
-  ui::TextInputClient* GetTextInputClient() override;
   void OnGestureEvent(ui::GestureEvent* event) override;
   void ShowContextMenu(const gfx::Point& p,
                        ui::MenuSourceType source_type) override;
@@ -330,6 +329,8 @@ class VIEWS_EXPORT TreeView : public ui::TreeModelObserver,
   // that previously wasn't.
   bool ExpandImpl(ui::TreeModelNode* model_node);
 
+  PrefixSelector* GetPrefixSelector();
+
   // The model, may be null.
   ui::TreeModel* model_;