split view: Fix split view drag indicators in multi-display dragging

Multi-display dragging was not accounted for in
https://chromium-review.googlesource.com/c/chromium/src/+/2039140

Test: ash_unittests All/SplitViewOverviewSessionInClamshellTestMultiDisplayOnly.MultiDisplayDragging/0
Bug: 961170
Change-Id: I9db1c280702e0197d24d4e18c8d4c7d441999061
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2055808Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741494}

ash/wm/overview/overview_session_unittest.cc

@@ -6347,6 +6347,19 @@ TEST_P(SplitViewOverviewSessionInClamshellTestMultiDisplayOnly,
                                            /*window_for_minimum_size=*/nullptr),
       grid_on_root2->bounds());
 
+  const gfx::PointF root2_left_snap_point_away_from_edge(816.f, 300.f);
+  overview_session()->Drag(item1, root2_left_snap_point_away_from_edge);
+  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kOtherDisplay,
+            indicators_on_root1->current_window_dragging_state());
+  EXPECT_EQ(display_with_root1.work_area(), grid_on_root1->bounds());
+  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kToSnapLeft,
+            indicators_on_root2->current_window_dragging_state());
+  EXPECT_EQ(
+      SplitViewController::Get(root_windows[1])
+          ->GetSnappedWindowBoundsInScreen(SplitViewController::RIGHT,
+                                           /*window_for_minimum_size=*/nullptr),
+      grid_on_root2->bounds());
+
   const gfx::PointF root2_right_snap_point(1599.f, 300.f);
   overview_session()->Drag(item1, root2_right_snap_point);
   EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kOtherDisplay,

ash/wm/splitview/split_view_utils.cc

@@ -476,7 +476,7 @@ SplitViewController::SnapPosition GetSnapPosition(
     drag_end_near_edge = true;
   }
 
-  if (!drag_end_near_edge) {
+  if (!drag_end_near_edge && window->GetRootWindow() == root_window) {
     // Check how far the window has been dragged.
     const auto distance = location_in_screen - initial_location_in_screen;
     const int primary_axis_distance = horizontal ? distance.x() : distance.y();