Introduce ViewRoot to forward input/view events to native

ui/android/window_android.cc

Index: ui/android/window_android.cc
diff --git a/ui/android/window_android.cc b/ui/android/window_android.cc
index cff32ba6f571def1c787cd219296027d86f1cbc8..4cd7fbf4efb8ada5df03a29b20913b72e6151324 100644
--- a/ui/android/window_android.cc
+++ b/ui/android/window_android.cc
@@ -132,6 +132,12 @@ void WindowAndroid::OnActivityStarted(JNIEnv* env,
     observer.OnActivityStarted();
 }
 
+ScopedJavaLocalRef<jobject> WindowAndroid::GetEventHandlerForJava(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& obj) {
+  return GetEventHandler();
+}
+
 bool WindowAndroid::HasPermission(const std::string& permission) {
   JNIEnv* env = AttachCurrentThread();
   return Java_WindowAndroid_hasPermission(