Make ViewRoot the top of the ViewAndroid tree

ui/display/screen.h

Index: ui/display/screen.h
diff --git a/ui/display/screen.h b/ui/display/screen.h
index 3bff5bdb6406f2bb5256fb552cb8642c5951b2dd..def1328c1db387060e85c0b56c7d51884b0f65f6 100644
--- a/ui/display/screen.h
+++ b/ui/display/screen.h
@@ -60,6 +60,12 @@ class DISPLAY_EXPORT Screen {
   // return the primary display.
   virtual Display GetDisplayNearestWindow(gfx::NativeView view) const = 0;
 
+#if defined(OS_ANDROID)
+  // This method is needed since NativeWindow is not a NativeView on Android.
+  virtual display::Display GetDisplayNearestWindowAndroid(

[boliu, 2017/02/13 22:58:08]

just Android part in this name and overload the method. style guide more or less
allows this kind of overloading

also maybe instead of OS_ANDROID, have a WINDOW_IS_NOT_VIEW define? although I
dunno if that works for all platforms yet..

oshima: wdyt?

[oshima, 2017/02/14 00:26:44]

+tapted@, benwells@

Maybe we should change this to NativeWindow to match the description and
name.They're the same on Aura. Only other platform they differ is mac/iOS. I
looked up mac code, and it may not be hard to change.

Ben, Trent, what do you think?

[tapted, 2017/02/14 00:58:00]

Yeah in screen_mac this always uses [view window] -- there's no attempt to see
whether a subview is actually on a different display for the case where a window
spans multiple displays. So switching GetDisplayNearestWindow to take a
gfx::NativeWindow should work fine.



(Also, when this comes up on Mac, there is stuff in
chrome/browser/platform_util.h to help:

gfx::NativeWindow GetTopLevel(gfx::NativeView view);
gfx::NativeView GetViewForWindow(gfx::NativeWindow window);

in platform_util_android.cc, GetTopLevel() is `NOTIMPLEMENTED()` but returns
something anyway

GetViewForWindow() on android might be a missing symbol

I don't really see a problem with moving these two methods to ui/gfx if that's
needed. E.g., if we needed/wanted to provide a non-virtual overload to help with
this change (since you can't passing `[view window]` to satisfy mac requires
Objective-C which can't be put in a .cc file).  see also
http://crbug.com/327611#c9

[Jinsuk Kim, 2017/02/14 05:09:59]

I think it is probably better to take this part out of this CL and create a new
one replacing gfx::NativeView with gfx::NativeWindow for
GetDisplayNearestWindow. Let me do that.

+      gfx::NativeWindow window) const = 0;
+#endif
+
   // Returns the display nearest the specified point. |point| should be in DIPs.
   virtual Display GetDisplayNearestPoint(const gfx::Point& point) const = 0;