Add setFocusedWindow function stub

This function, once implemented, will set focus on the specified
window. This is the first step in changing focus selection from
setInputWindows and using explicit call which will help us more
easily decouple z-order from focus selection and support focus
for SurfaceViewHost surfaces.

Bug: 151179149
Test: presubmit
Test: go/wm-smoke
Test: atest inputflinger_tests

Change-Id: Ib2254b4ab3ba8d579dfe49ddf3286f8ce2eecf9e
diff --git a/services/inputflinger/dispatcher/InputDispatcher.h b/services/inputflinger/dispatcher/InputDispatcher.h
index ba7ace0..b4d1079 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.h
+++ b/services/inputflinger/dispatcher/InputDispatcher.h
@@ -126,6 +126,7 @@
 
     virtual status_t registerInputChannel(
             const std::shared_ptr<InputChannel>& inputChannel) override;
+    virtual void setFocusedWindow(const FocusRequest&) override;
     virtual status_t registerInputMonitor(const std::shared_ptr<InputChannel>& inputChannel,
                                           int32_t displayId, bool isGestureMonitor) override;
     virtual status_t unregisterInputChannel(const InputChannel& inputChannel) override;