Make ViewRoot the top of the ViewAndroid tree

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 8a0c8c368ff47df37ddff87326fe0b8819359655..e9b777fb599791d5a36a62563d9638ce971e7473 100644
--- a/ui/android/window_android.cc
+++ b/ui/android/window_android.cc
@@ -129,7 +129,6 @@ bool WindowAndroid::RegisterWindowAndroid(JNIEnv* env) {
 }
 
 WindowAndroid::~WindowAndroid() {
-  DCHECK(parent_ == nullptr) << "WindowAndroid must be a root view.";
   DCHECK(!compositor_);
   Java_WindowAndroid_clearNativePointer(AttachCurrentThread(), GetJavaObject());
 }
@@ -258,11 +257,6 @@ 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
 // ----------------------------------------------------------------------------