Enable Config::MUS to use classic IME instead of servicified IME.

ui/aura/mus/window_tree_host_mus.h

Index: ui/aura/mus/window_tree_host_mus.h
diff --git a/ui/aura/mus/window_tree_host_mus.h b/ui/aura/mus/window_tree_host_mus.h
index b84efb4de91348693ebee5fa1641fd4bae9d2c97..6d777f9f116d153bf30db0b3caaf80a57f1fa8f1 100644
--- a/ui/aura/mus/window_tree_host_mus.h
+++ b/ui/aura/mus/window_tree_host_mus.h
@@ -20,6 +20,10 @@ namespace display {
 class Display;
 }
 
+namespace ui {
+class InputMethodChromeOS;
+}
+
 namespace aura {
 
 class InputMethodMus;
@@ -45,7 +49,13 @@ class AURA_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
     return aura::WindowTreeHostPlatform::SendEventToSink(event);
   }
 
-  InputMethodMus* input_method() { return input_method_.get(); }
+  InputMethodMus* input_method_mus_for_testing() {
+    return input_method_mus_.get();
+  }
+
+  void DispatchEventToInputMethod(
+      ui::KeyEvent* event,
+      std::unique_ptr<base::Callback<void(bool)>> ack_callback);
 
   // Sets the client area on the underlying mus window.
   void SetClientArea(const gfx::Insets& insets,
@@ -96,13 +106,19 @@ class AURA_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
       const gfx::Point& location_in_pixels) override;
 
  private:
+  void InitInputMethod(WindowTreeHostMusInitParams* init_params);
+
   int64_t display_id_;
 
   WindowTreeHostMusDelegate* delegate_;
 
   bool in_set_bounds_from_server_ = false;
 
-  std::unique_ptr<InputMethodMus> input_method_;
+  std::unique_ptr<InputMethodMus> input_method_mus_;
+
+#if defined(OS_CHROMEOS)
+  std::unique_ptr<ui::InputMethodChromeOS> input_method_chromeos_;
+#endif
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHostMus);
 };