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 535aeb2fb07afa4eadcaf2f56876bb93af293314..6f1bbf9c49e37bc1c49b8c64b0ad37a3e11fda58 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(shell::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);
 };