Remove window/host accessors from WED; IWYU for WTH

ash/accelerators/key_hold_detector.cc

Index: ash/accelerators/key_hold_detector.cc
diff --git a/ash/accelerators/key_hold_detector.cc b/ash/accelerators/key_hold_detector.cc
index 0908c2cd9429c0d15100fe967820b87213380931..179d4f3cb2eea734c8ba3e87bcbbf4fddf630c17 100644
--- a/ash/accelerators/key_hold_detector.cc
+++ b/ash/accelerators/key_hold_detector.cc
@@ -11,9 +11,10 @@
 
 #include "ash/shell.h"
 #include "base/message_loop/message_loop.h"
-#include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tracker.h"
+#include "ui/aura/window_tree_host.h"
 #include "ui/events/event_dispatcher.h"
+#include "ui/events/event_processor.h"
 
 namespace ash {
 namespace {
@@ -27,7 +28,7 @@ void DispatchPressedEvent(XEvent native_event,
   ui::KeyEvent event(&native_event, false);
   event.set_flags(event.flags() | ui::EF_IS_SYNTHESIZED);
   ui::EventDispatchDetails result ALLOW_UNUSED =
-      target->GetHost()->dispatcher()->OnEventFromSource(&event);
+      target->GetHost()->event_processor()->OnEventFromSource(&event);
 }
 
 void PostPressedEvent(ui::KeyEvent* event) {