Supports fake key events for setComposition/commitText by on-screen keyboards.

ui/wm/core/input_method_event_filter.cc

Index: ui/wm/core/input_method_event_filter.cc
diff --git a/ui/wm/core/input_method_event_filter.cc b/ui/wm/core/input_method_event_filter.cc
index 65bd5b506460b61d7dbe6c43a43f13f15882fe3f..10e5e5ad286685f3fb54df0de0711483324efac3 100644
--- a/ui/wm/core/input_method_event_filter.cc
+++ b/ui/wm/core/input_method_event_filter.cc
@@ -63,16 +63,16 @@ void InputMethodEventFilter::OnKeyEvent(ui::KeyEvent* event) {
     // IME again.  Just let the event dispatcher continue to dispatch the event.
     event->SetTranslated(false);
   } else {
-    // If the focused window is changed, all requests to IME will be
-    // discarded so it's safe to update the target_dispatcher_ here.
-    aura::Window* target = static_cast<aura::Window*>(event->target());
-    target_dispatcher_ = target->GetRootWindow()->GetHost()->event_processor();
-    DCHECK(target_dispatcher_);
     if (input_method_->DispatchKeyEvent(*event))
       event->StopPropagation();
   }
 }
 
+void InputMethodEventFilter::UpdateTargetDispatcher(
+    ui::EventProcessor* dispatcher) {
+  target_dispatcher_ = dispatcher;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // InputMethodEventFilter, ui::InputMethodDelegate implementation:
 
@@ -86,6 +86,8 @@ bool InputMethodEventFilter::DispatchKeyEventPostIME(
   // This time we have to skip dispatching the event to the IME, we mark the
   // event as TRANSLATED so we can distinguish this event as a second time
   // dispatched event.
+  if (!target_dispatcher_)
+    return false;
   ui::KeyEvent aura_event(event);
   aura_event.SetTranslated(true);
   ui::EventDispatchDetails details =