Revert of Remove InputMethodEventHandler.

ash/test/ash_test_base.cc

Index: ash/test/ash_test_base.cc
diff --git a/ash/test/ash_test_base.cc b/ash/test/ash_test_base.cc
index f4104033b40b18353634b70609fbff260e3bc309..2c22ca48476a739fcd36ce4335b4e56900e445e8 100644
--- a/ash/test/ash_test_base.cc
+++ b/ash/test/ash_test_base.cc
@@ -11,6 +11,7 @@
 #include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/display/unified_mouse_warp_controller.h"
 #include "ash/display/window_tree_host_manager.h"
+#include "ash/ime/input_method_event_handler.h"
 #include "ash/mus/top_level_window_factory.h"
 #include "ash/mus/window_manager.h"
 #include "ash/mus/window_manager_application.h"
@@ -36,7 +37,6 @@
 #include "ui/aura/client/window_parenting_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/mus/property_converter.h"
-#include "ui/aura/test/aura_test_utils.h"
 #include "ui/aura/test/event_generator_delegate_aura.h"
 #include "ui/aura/test/test_window_delegate.h"
 #include "ui/aura/window.h"
@@ -454,7 +454,13 @@
 }
 
 void AshTestBase::DisableIME() {
-  aura::test::DisableIME(Shell::GetPrimaryRootWindow()->GetHost());
+  // WindowTreeHostManager isn't applicable to mash and IME is routed
+  // differently in mash.
+  if (Shell::GetAshConfig() == Config::MASH)
+    return;
+
+  Shell::Get()->RemovePreTargetHandler(
+      Shell::Get()->window_tree_host_manager()->input_method_event_handler());
 }
 
 display::DisplayManager* AshTestBase::display_manager() {