Start to decouple display::Display from ws::PlatformDisplay.

services/ui/ws/window_manager_state.cc

Index: services/ui/ws/window_manager_state.cc
diff --git a/services/ui/ws/window_manager_state.cc b/services/ui/ws/window_manager_state.cc
index c25923222eb392af2d5fa36003a1c3c7f28e0bad..dc32df45a8f2bfff86c37ec2eb58f8f040cee290 100644
--- a/services/ui/ws/window_manager_state.cc
+++ b/services/ui/ws/window_manager_state.cc
@@ -632,7 +632,7 @@ ServerWindow* WindowManagerState::GetRootWindowContaining(
 
   WindowManagerDisplayRoot* target_display_root = nullptr;
   for (auto& display_root_ptr : window_manager_display_roots_) {
-    if (display_root_ptr->display()->platform_display()->GetBounds().Contains(
+    if (display_root_ptr->display()->GetDisplay().bounds().Contains(
             *location)) {
       target_display_root = display_root_ptr.get();
       break;
@@ -649,7 +649,7 @@ ServerWindow* WindowManagerState::GetRootWindowContaining(
   // Translate the location to be relative to the display instead of relative
   // to the screen space.
   gfx::Point origin =
-      target_display_root->display()->platform_display()->GetBounds().origin();
+      target_display_root->display()->GetDisplay().bounds().origin();
   *location -= origin.OffsetFromOrigin();
   return target_display_root->root();
 }