[Merge to M-76] Overview: Fix a crash when window is long pressed and not moved

TBR=​xdai@chromium.org
BUG=972807
TEST=Manual

(cherry picked from commit 8f7ad7a2cc7cb75b0bea05c127a89cdf2742daca)

Change-Id: Ib81da2b88eb2dd4831ce9bcb8192d976974e31e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1650956
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#667798}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1653086
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/branch-heads/3809@{#240}
Cr-Branched-From: d82dec1a818f378c464ba307ddd9c92133eac355-refs/heads/master@{#665002}

diff --git a/ash/wm/overview/overview_window_drag_controller.cc b/ash/wm/overview/overview_window_drag_controller.cc
index 6aa4928..d055e35 100644
--- a/ash/wm/overview/overview_window_drag_controller.cc
+++ b/ash/wm/overview/overview_window_drag_controller.cc

@@ -259,8 +259,10 @@
     Shell::Get()->mouse_cursor_filter()->HideSharedEdgeIndicator();
     item_->DestroyPhantomsForDragging();
     item_->overview_grid()->RemoveDropTarget();
-    overview_session_->SetSplitViewDragIndicatorsIndicatorState(
-        IndicatorState::kNone, gfx::Point());
+    if (should_allow_split_view_) {
+      overview_session_->SetSplitViewDragIndicatorsIndicatorState(
+          IndicatorState::kNone, gfx::Point());
+    }
   }
   overview_session_->PositionWindows(/*animate=*/true);
   // This function gets called after a long press release, which bypasses