Revert of Remove InputMethodEventHandler.

ash/host/ash_window_tree_host_platform.cc

Index: ash/host/ash_window_tree_host_platform.cc
diff --git a/ash/host/ash_window_tree_host_platform.cc b/ash/host/ash_window_tree_host_platform.cc
index 932e6b60a0014e10313a1a85a9e8b86a4b155c2c..9da128d74cc535c15bae69bc6b61d63210e2b1ed 100644
--- a/ash/host/ash_window_tree_host_platform.cc
+++ b/ash/host/ash_window_tree_host_platform.cc
@@ -8,6 +8,7 @@
 
 #include "ash/host/root_window_transformer.h"
 #include "ash/host/transformer_helper.h"
+#include "ash/ime/input_method_event_handler.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host_platform.h"
@@ -114,6 +115,15 @@
   SendEventToSink(event);
 }
 
+ui::EventDispatchDetails AshWindowTreeHostPlatform::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 AshWindowTreeHostPlatform::SetTapToClickPaused(bool state) {
 #if defined(USE_OZONE)
   DCHECK(ui::OzonePlatform::GetInstance()->GetInputController());