Introduce ViewRoot forwarding 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 770fda4bde502d16a39f5dd0a5660e5fbdac6a32..b528b050bf643c4c4c05a1d9fe9ff3a3730ce188 100644
--- a/ui/android/window_android.cc
+++ b/ui/android/window_android.cc
@@ -150,7 +150,6 @@ bool WindowAndroid::RegisterWindowAndroid(JNIEnv* env) {
 }
 
 WindowAndroid::~WindowAndroid() {
-  DCHECK(parent_ == nullptr) << "WindowAndroid must be a root view.";
   DCHECK(!compositor_);
   Java_WindowAndroid_clearNativePointer(AttachCurrentThread(), GetJavaObject());
 }
@@ -255,12 +254,6 @@ void WindowAndroid::OnActivityStarted(JNIEnv* env,
     observer.OnActivityStarted();
 }
 
-ScopedJavaLocalRef<jobject> WindowAndroid::GetViewRootForJava(
-    JNIEnv* env,
-    const base::android::JavaParamRef<jobject>& obj) {
-  return GetViewRoot();
-}
-
 bool WindowAndroid::HasPermission(const std::string& permission) {
   JNIEnv* env = AttachCurrentThread();
   return Java_WindowAndroid_hasPermission(
@@ -275,11 +268,6 @@ bool WindowAndroid::CanRequestPermission(const std::string& permission) {
       base::android::ConvertUTF8ToJavaString(env, permission));
 }
 
-WindowAndroid* WindowAndroid::GetWindowAndroid() const {
-  DCHECK(parent_ == nullptr);
-  return const_cast<WindowAndroid*>(this);
-}
-
 // ----------------------------------------------------------------------------
 // Native JNI methods
 // ----------------------------------------------------------------------------