Revert of Remove InputMethodEventHandler.

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 92616f6d1a2ee8cfdd554ffccaeaa5557eaab005..1d0284243fded2b80b215e974d6f699960c118f6 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -41,6 +41,7 @@
 #include "ash/frame/custom_frame_view_ash.h"
 #include "ash/gpu_support.h"
 #include "ash/high_contrast/high_contrast_controller.h"
+#include "ash/ime/input_method_event_handler.h"
 #include "ash/keyboard/keyboard_ui.h"
 #include "ash/laser/laser_pointer_controller.h"
 #include "ash/login/lock_screen_controller.h"
@@ -621,6 +622,10 @@ Shell::~Shell() {
   // Please keep in same order as in Init() because it's easy to miss one.
   if (window_modality_controller_)
     window_modality_controller_.reset();
+  if (config != Config::MASH) {
+    RemovePreTargetHandler(
+        window_tree_host_manager_->input_method_event_handler());
+  }
 
   RemovePreTargetHandler(magnifier_key_scroll_handler_.get());
   magnifier_key_scroll_handler_.reset();
@@ -951,6 +956,13 @@ void Shell::Init(const ShellInitParams& init_params) {
   accelerator_controller_ = shell_port_->CreateAcceleratorController();
   maximize_mode_controller_ = base::MakeUnique<MaximizeModeController>();
 
+  if (!ShouldUseIMEService()) {
+    // Not applicable when using IME service as events are already routed to
+    // InputMethod first.
+    AddPreTargetHandler(
+        window_tree_host_manager_->input_method_event_handler());
+  }
+
   magnifier_key_scroll_handler_ = MagnifierKeyScroller::CreateHandler();
   AddPreTargetHandler(magnifier_key_scroll_handler_.get());
   speech_feedback_handler_ = SpokenFeedbackToggler::CreateHandler();