Make ViewRoot the top of the ViewAndroid tree

ui/android/dummy_screen_android.cc

Index: ui/android/dummy_screen_android.cc
diff --git a/ui/android/dummy_screen_android.cc b/ui/android/dummy_screen_android.cc
index 28520b8abb9a8e8ba0fa15f9303c5acc11cc9644..bf709e89dc39ccc11792c33b2c7ac6575191dbfc 100644
--- a/ui/android/dummy_screen_android.cc
+++ b/ui/android/dummy_screen_android.cc
@@ -43,6 +43,11 @@ class DummyScreenAndroid : public display::Screen {
     return GetPrimaryDisplay();
   }
 
+  Display GetDisplayNearestWindowAndroid(
+      gfx::NativeWindow window) const override {
+    return GetPrimaryDisplay();
+  }
+
   Display GetDisplayNearestPoint(const gfx::Point& point) const override {
     return GetPrimaryDisplay();
   }