Introduce ViewRoot forwarding input/view events to native

ui/android/BUILD.gn

Index: ui/android/BUILD.gn
diff --git a/ui/android/BUILD.gn b/ui/android/BUILD.gn
index 98d80b4dd5d9bd95cd7e08430db350052816d724..4ef678756a6270d798eae6e1c5fa85f43081133c 100644
--- a/ui/android/BUILD.gn
+++ b/ui/android/BUILD.gn
@@ -42,6 +42,10 @@ component("android") {
     "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",
@@ -59,6 +63,7 @@ component("android") {
     "//cc/surfaces:surface_id",
     "//skia",
     "//ui/display",
+    "//ui/events",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
@@ -81,6 +86,7 @@ generate_jni("ui_android_jni_headers") {
   sources = [
     "java/src/org/chromium/ui/OverscrollRefreshHandler.java",
     "java/src/org/chromium/ui/base/ViewAndroidDelegate.java",
+    "java/src/org/chromium/ui/base/ViewRoot.java",
     "java/src/org/chromium/ui/base/WindowAndroid.java",
     "java/src/org/chromium/ui/display/DisplayAndroidManager.java",
     "java/src/org/chromium/ui/resources/ResourceManager.java",
@@ -176,6 +182,7 @@ android_library("ui_java") {
     "java/src/org/chromium/ui/base/SelectFileDialog.java",
     "java/src/org/chromium/ui/base/TouchDevice.java",
     "java/src/org/chromium/ui/base/ViewAndroidDelegate.java",
+    "java/src/org/chromium/ui/base/ViewRoot.java",
     "java/src/org/chromium/ui/base/WindowAndroid.java",
     "java/src/org/chromium/ui/display/DisplayAndroid.java",
     "java/src/org/chromium/ui/display/DisplayAndroidManager.java",
@@ -243,6 +250,7 @@ test("ui_android_unittests") {
     "overscroll_refresh_unittest.cc",
     "resources/resource_manager_impl_unittest.cc",
     "run_all_unittests.cc",
+    "view_android_unittest.cc",
   ]
   deps = [
     ":android",
@@ -256,6 +264,7 @@ test("ui_android_unittests") {
     "//testing/gmock",
     "//testing/gtest",
     "//ui/base",
+    "//ui/events",
     "//ui/gfx",
     "//ui/resources:ui_test_pak",
   ]