ViewRoot class for event forwarding on Android

ui/android/BUILD.gn

Index: ui/android/BUILD.gn
diff --git a/ui/android/BUILD.gn b/ui/android/BUILD.gn
index 243e57f4b6e5217f4e9b109e2e115cd7657f27e5..bc9223a5cd4779838cb517e39ec381e410529359 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",
@@ -81,6 +85,7 @@ 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 +181,7 @@ 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",
@@ -246,6 +252,7 @@ test("ui_android_unittests") {
     "overscroll_refresh_unittest.cc",
     "resources/resource_manager_impl_unittest.cc",
     "run_all_unittests.cc",
+    "view_android_unittest.cc",
   ]
   deps = [
     ":android",