Revert of Remove InputMethodEventHandler.

ash/host/ash_window_tree_host.h

Index: ash/host/ash_window_tree_host.h
diff --git a/ash/host/ash_window_tree_host.h b/ash/host/ash_window_tree_host.h
index c52ee185eb5619b49601a6e19530f6e09811c3a6..dfe20f5ec327959aa6a3ddc58896012b04e50f6d 100644
--- a/ash/host/ash_window_tree_host.h
+++ b/ash/host/ash_window_tree_host.h
@@ -23,6 +23,7 @@ class LocatedEvent;
 
 namespace ash {
 struct AshWindowTreeHostInitParams;
+class InputMethodEventHandler;
 class RootWindowTransformer;
 
 class ASH_EXPORT AshWindowTreeHost {
@@ -33,6 +34,14 @@ class ASH_EXPORT AshWindowTreeHost {
   static std::unique_ptr<AshWindowTreeHost> Create(
       const AshWindowTreeHostInitParams& init_params);
 
+  void set_input_method_handler(InputMethodEventHandler* input_method_handler) {
+    input_method_handler_ = input_method_handler;
+  }
+
+  InputMethodEventHandler* input_method_handler() {
+    return input_method_handler_;
+  }
+
   // Toggles the host's full screen state.
   virtual void ToggleFullScreen() = 0;
 
@@ -59,6 +68,9 @@ class ASH_EXPORT AshWindowTreeHost {
  protected:
   // Translates the native mouse location into screen coordinates.
   void TranslateLocatedEvent(ui::LocatedEvent* event);
+
+ private:
+  InputMethodEventHandler* input_method_handler_;
 };
 
 }  // namespace ash