Introduce ViewRoot forwarding input/view events to native

ui/android/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.
 
 import("//build/config/android/rules.gni")
 import("//testing/test.gni")
 
 assert(is_android)
 
 component("android") {
@@ skipping 26 matching lines @@
     "resources/resource_manager_impl.h",
     "resources/ui_resource_provider.h",
     "screen_android.h",
     "ui_android_export.h",
     "ui_android_jni_registrar.cc",
     "ui_android_jni_registrar.h",
     "view_android.cc",
     "view_android.h",
     "view_client.cc",
     "view_client.h",
+    "view_root.cc",
+    "view_root.h",
     "window_android.cc",
     "window_android.h",
     "window_android_compositor.h",
     "window_android_observer.h",
   ]
 
   defines = [ "UI_ANDROID_IMPLEMENTATION" ]
 
   deps = [
     ":java_enums_srcjar",
@@ skipping 201 matching lines @@
     "//cc",
     "//cc:test_support",
     "//skia",
     "//testing/gmock",
     "//testing/gtest",
     "//ui/base",
     "//ui/gfx",
     "//ui/resources:ui_test_pak",
   ]
 }