Change OnWindowInputEvent to use display_id to find the host and update event root_location in WS.

services/ui/ws/test_change_tracker.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SERVICES_UI_WS_TEST_CHANGE_TRACKER_H_
 #define SERVICES_UI_WS_TEST_CHANGE_TRACKER_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 62 matching lines @@
   ClientSpecificId client_id;
   std::vector<TestWindow> windows;
   Id window_id;
   Id window_id2;
   Id window_id3;
   gfx::Rect bounds;
   gfx::Rect bounds2;
   base::Optional<cc::LocalSurfaceId> local_surface_id;
   int32_t event_action;
   bool matches_pointer_watcher;
+  gfx::Point event_root_location;
   std::string embed_url;
   mojom::OrderDirection direction;
   bool bool_value;
   float float_value;
   std::string property_key;
   std::string property_value;
   int32_t cursor_id;
   uint32_t change_id;
   cc::SurfaceId surface_id;
   gfx::Size frame_size;
@@ skipping 93 matching lines @@
   std::vector<Change> changes_;
 
   DISALLOW_COPY_AND_ASSIGN(TestChangeTracker);
 };
 
 }  // namespace ws
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_TEST_CHANGE_TRACKER_H_