Revert of Remove InputMethodEventHandler.

ash/host/ash_window_tree_host_x11.cc

Index: ash/host/ash_window_tree_host_x11.cc
diff --git a/ash/host/ash_window_tree_host_x11.cc b/ash/host/ash_window_tree_host_x11.cc
index 73efb44b96602b3f7322edb05423962a757f9193..6733d78f82ab8d4f494435ff6685c7c73c2b342e 100644
--- a/ash/host/ash_window_tree_host_x11.cc
+++ b/ash/host/ash_window_tree_host_x11.cc
@@ -15,6 +15,7 @@
 #include "ash/host/ash_window_tree_host_init_params.h"
 #include "ash/host/ash_window_tree_host_unified.h"
 #include "ash/host/root_window_transformer.h"
+#include "ash/ime/input_method_event_handler.h"
 #include "base/sys_info.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window.h"
@@ -212,6 +213,15 @@ void AshWindowTreeHostX11::TranslateAndDispatchLocatedEvent(
   SendEventToSink(event);
 }
 
+ui::EventDispatchDetails AshWindowTreeHostX11::DispatchKeyEventPostIME(
+    ui::KeyEvent* event) {
+  input_method_handler()->SetPostIME(true);
+  ui::EventDispatchDetails details = event_sink()->OnEventFromSource(event);
+  if (!details.dispatcher_destroyed)
+    input_method_handler()->SetPostIME(false);
+  return details;
+}
+
 void AshWindowTreeHostX11::SetCrOSTapPaused(bool state) {
   if (!ui::IsXInput2Available())
     return;