Introduce ViewRoot to forward 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 4ee7b108e9644faf358f11ef6b9c6d93914683cc..5e44d1f5bd002b12e51ac31d212bb21aa18bab5e 100644
--- a/ui/android/BUILD.gn
+++ b/ui/android/BUILD.gn
@@ -42,6 +42,8 @@ component("android") {
     "ui_android_jni_registrar.h",
     "view_android.cc",
     "view_android.h",
+    "view_client.cc",
+    "view_client.h",
     "window_android.cc",
     "window_android.h",
     "window_android_compositor.h",
@@ -81,6 +83,7 @@ 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 +179,7 @@ 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",