IME for Mus: Send ack for key events after IME driver processes the event.

ui/views/mus/window_tree_host_mus.h

Index: ui/views/mus/window_tree_host_mus.h
diff --git a/ui/views/mus/window_tree_host_mus.h b/ui/views/mus/window_tree_host_mus.h
index 9afca038db51866c294327d66c404b7d319535a7..84c4649e85265b581ab6e629a20fc7d179514358 100644
--- a/ui/views/mus/window_tree_host_mus.h
+++ b/ui/views/mus/window_tree_host_mus.h
@@ -22,7 +22,6 @@ class Connector;
 
 namespace views {
 
-class InputMethodMus;
 class NativeWidgetMus;
 class PlatformWindowMus;
 
@@ -32,8 +31,6 @@ class VIEWS_MUS_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
   ~WindowTreeHostMus() override;
   NativeWidgetMus* native_widget() { return native_widget_; }
 
-  void InitInputMethod(service_manager::Connector* connector);
-
  private:
   // aura::WindowTreeHostPlatform:
   void DispatchEvent(ui::Event* event) override;
@@ -43,7 +40,6 @@ class VIEWS_MUS_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
   gfx::ICCProfile GetICCProfileForCurrentDisplay() override;
 
   NativeWidgetMus* native_widget_;
-  std::unique_ptr<InputMethodMus> input_method_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHostMus);
 };