Makes DesktopWindowTreeHostXxx to dispatch key event to InputMethod.

ash/host/ash_window_tree_host_win.cc

Index: ash/host/ash_window_tree_host_win.cc
diff --git a/ash/host/ash_window_tree_host_win.cc b/ash/host/ash_window_tree_host_win.cc
index 3c6a1a1577a3ffc9153664d949b38679c9bda84f..8064f83cef9a2c01789bc59d06bd7b8475161924 100644
--- a/ash/host/ash_window_tree_host_win.cc
+++ b/ash/host/ash_window_tree_host_win.cc
@@ -14,6 +14,7 @@
 #include "base/command_line.h"
 #include "base/win/windows_version.h"
 #include "ui/aura/window_tree_host_win.h"
+#include "ui/events/event_processor.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/transform.h"
 
@@ -106,16 +107,13 @@ class AshWindowTreeHostWin : public AshWindowTreeHost,
   bool DispatchKeyEventPostIME(const ui::KeyEvent& event) override {
     ui::KeyEvent event_copy(event);
     input_method_handler()->SetPostIME(true);
-    ui::EventSource::DeliverEventToProcessor(&event_copy);
+    ui::EventDispatchDetails details =
+        event_processor()->OnEventFromSource(&event_copy);
+    DCHECK(!details.dispatcher_destroyed);
     input_method_handler()->SetPostIME(false);
     return event_copy.stopped_propagation();
   }
 
-  // ui::EventSource:
-  ui::EventDispatchDetails DeliverEventToProcessor(ui::Event* event) override {
-    return ui::EventSource::DeliverEventToProcessor(event);
-  }
-
   bool fullscreen_;
   RECT saved_window_rect_;
   DWORD saved_window_style_;