Make ViewRoot the top of the ViewAndroid tree

ui/display/test/test_screen.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <vector>
 
 #include "ui/display/test/test_screen.h"
 
 namespace display {
 namespace test {
@@ skipping 14 matching lines @@
 }
 
 gfx::NativeWindow TestScreen::GetWindowAtScreenPoint(const gfx::Point& point) {
   return nullptr;
 }
 
 Display TestScreen::GetDisplayNearestWindow(gfx::NativeView view) const {
   return GetPrimaryDisplay();
 }
 
+#if defined(OS_ANDROID)
+Display TestScreen::GetDisplayNearestWindowAndroid(
+    gfx::NativeWindow window) const {
+  return GetPrimaryDisplay();
+}
+#endif
+
 }  // namespace test
 }  // namespace display