Move |ScopedWebInputEvent| and |WebInputEventTraits| from |content::| to "ui/events/blink"

ui/events/blink/BUILD.gn

 # Copyright 2015 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.
 
 source_set("blink") {
   sources = [
     "blink_event_util.cc",
     "blink_event_util.h",
     "did_overscroll_params.cc",
     "did_overscroll_params.h",
     "input_handler_proxy.cc",
     "input_handler_proxy.h",
     "input_handler_proxy_client.h",
     "input_scroll_elasticity_controller.cc",
     "input_scroll_elasticity_controller.h",
+    "scoped_web_input_event.cc",
+    "scoped_web_input_event.h",
     "synchronous_input_handler_proxy.h",
+    "web_input_event_traits.cc",
+    "web_input_event_traits.h",
   ]
 
   deps = [
     "//cc:cc",
     "//third_party/WebKit/public:blink_headers",
     "//ui/events",
     "//ui/events:events_base",
     "//ui/events:gesture_detection",
     "//ui/gfx/geometry",
   ]
 }