Make ViewRoot the top of the ViewAndroid tree

ui/android/dummy_screen_android.cc

 // Copyright 2016 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 "ui/android/dummy_screen_android.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 
 namespace ui {
 
@@ skipping 25 matching lines @@
   int GetNumDisplays() const override { return 1; }
 
   const std::vector<Display>& GetAllDisplays() const override {
     return displays_;
   }
 
   Display GetDisplayNearestWindow(gfx::NativeView view) const override {
     return GetPrimaryDisplay();
   }
 
+  Display GetDisplayNearestWindowAndroid(
+      gfx::NativeWindow window) const override {
+    return GetPrimaryDisplay();
+  }
+
   Display GetDisplayNearestPoint(const gfx::Point& point) const override {
     return GetPrimaryDisplay();
   }
 
   Display GetDisplayMatching(const gfx::Rect& match_rect) const override {
     return GetPrimaryDisplay();
   }
 
   Display GetPrimaryDisplay() const override { return displays_[0]; }
 
   void AddObserver(DisplayObserver* observer) override {}
   void RemoveObserver(DisplayObserver* observer) override {}
 
  private:
   std::vector<Display> displays_;
 };
 
 display::Screen* CreateDummyScreenAndroid() {
   return new DummyScreenAndroid;
 }
 
 }  // namespace ui