GN: ui/events/platform target from r270816

ui/events/BUILD.gn

Index: ui/events/BUILD.gn
diff --git a/ui/events/BUILD.gn b/ui/events/BUILD.gn
index 1aae11ff16368397dc73676aabea7e83038cf0fd..e2fe42b84dd97aa35d2d461bbc7a2914f52f7dd7 100644
--- a/ui/events/BUILD.gn
+++ b/ui/events/BUILD.gn
@@ -44,6 +44,7 @@ component("events_base") {
     "//base",
     "//base/third_party/dynamic_annotations",
     "//skia",
+    "//ui/events/platform",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
@@ -110,14 +111,6 @@ component("events") {
     "gestures/gesture_types.h",
     "gestures/velocity_calculator.cc",
     "gestures/velocity_calculator.h",
-    "platform/platform_event_dispatcher.h",
-    "platform/platform_event_observer.h",
-    "platform/platform_event_source.cc",
-    "platform/platform_event_source.h",
-    "platform/platform_event_source_stub.cc",
-    "platform/platform_event_types.h",
-    "platform/scoped_event_dispatcher.cc",
-    "platform/scoped_event_dispatcher.h",
     "platform/x11/x11_event_source.cc",
     "platform/x11/x11_event_source.h",
     "win/events_win.cc",