Make ViewRoot the top of the ViewAndroid tree

ui/android/display_android_manager.h

Index: ui/android/display_android_manager.h
diff --git a/ui/android/display_android_manager.h b/ui/android/display_android_manager.h
index 9eae6fac7383d25f316096e608828bd690412835..2175054e56e437c5d9f8c41ed48225496a490b27 100644
--- a/ui/android/display_android_manager.h
+++ b/ui/android/display_android_manager.h
@@ -9,6 +9,7 @@
 
 #include "base/android/jni_android.h"
 #include "base/macros.h"
+#include "ui/android/ui_android_export.h"
 #include "ui/display/screen_base.h"
 
 namespace ui {
@@ -17,9 +18,14 @@ class DisplayAndroidManager : public display::ScreenBase {
  public:
   ~DisplayAndroidManager() override;
 
+  // Prefer using |Screen::GetScreen()|. Only use this to avoid casting.
+  static DisplayAndroidManager* GetInstance();
+
   // Screen interface.
 
   display::Display GetDisplayNearestWindow(gfx::NativeView view) const override;
+  display::Display GetDisplayNearestWindowAndroid(
+      gfx::NativeWindow window) const override;
   display::Display GetDisplayNearestPoint(
       const gfx::Point& point) const override;
   display::Display GetDisplayMatching(