cros: Prevent a window drag towards bottom of screen moving shelf

This shouldn't move the shelf or hotseat.

Bug: 1025080
Change-Id: I70f48b99e96ca590890706edc84b623509bb561d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919629
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Manu Cornet <manucornet@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716423}

ash/shelf/shelf_layout_manager.cc

@@ -1748,8 +1748,13 @@ void ShelfLayoutManager::UpdateTargetBoundsForGesture(
     if (move_shelf_with_hotseat) {
       // Do not allow the shelf to be dragged more than |shelf_size| from the
       // bottom of the display.
-      const int shelf_y = std::max(available_bounds.bottom() - shelf_size,
-                                   static_cast<int>(baseline + translate));
+      int shelf_y = std::max(available_bounds.bottom() - shelf_size,
+                             static_cast<int>(baseline + translate));
+      // Window drags only happen after the hotseat has been dragged up to its
+      // full height. After the drag moves a window, do not allow the drag to
+      // move the hotseat down.
+      if (IsWindowDragInProgress())
+        shelf_y = available_bounds.bottom() - shelf_size;
       target_bounds_.shelf_bounds.set_y(shelf_y);
     }
 
@@ -1769,6 +1774,11 @@ void ShelfLayoutManager::UpdateTargetBoundsForGesture(
         -hotseat_extended_y,
         static_cast<int>((use_hotseat_baseline ? hotseat_baseline : 0) +
                          translate));
+    // Window drags only happen after the hotseat has been dragged up to its
+    // full height. After the drag moves a window, do not allow the drag to move
+    // the hotseat down.
+    if (IsWindowDragInProgress())
+      hotseat_y = -hotseat_extended_y;
     target_bounds_.hotseat_bounds_in_shelf.set_y(hotseat_y);
     return;
   }
@@ -2630,7 +2640,7 @@ void ShelfLayoutManager::MaybeCancelWindowDrag() {
   window_drag_controller_->CancelDrag();
 }
 
-bool ShelfLayoutManager::IsWindowDragInProgress() {
+bool ShelfLayoutManager::IsWindowDragInProgress() const {
   return window_drag_controller_ && window_drag_controller_->drag_started();
 }
 

ash/shelf/shelf_layout_manager.h

@@ -527,7 +527,7 @@ class ASH_EXPORT ShelfLayoutManager : public AppListControllerObserver,
   base::Optional<DragWindowFromShelfController::ShelfWindowDragResult>
   MaybeEndWindowDrag(const ui::LocatedEvent& event_in_screen);
   void MaybeCancelWindowDrag();
-  bool IsWindowDragInProgress();
+  bool IsWindowDragInProgress() const;
 
   // True when inside UpdateBoundsAndOpacity() method. Used to prevent calling
   // UpdateBoundsAndOpacity() again from SetChildBounds().

ash/shelf/shelf_layout_manager_unittest.cc

@@ -4872,6 +4872,64 @@ TEST_F(ShelfLayoutManagerWindowDraggingTest, DISABLED_NoOpForHiddenShelf) {
   EndScroll(/*is_fling=*/false, 0.f);
 }
 
+// Tests that dragging below the hotseat after dragging the MRU up results in
+// the hotseat not moving from its extended position.
+TEST_F(ShelfLayoutManagerWindowDraggingTest,
+       DragBelowHotseatDoesNotMoveHotseat) {
+  // Go to in-app shelf, then drag the hotseat up until it is extended, this
+  // will start a window drag.
+  std::unique_ptr<aura::Window> window =
+      AshTestBase::CreateTestWindow(gfx::Rect(0, 0, 400, 400));
+  wm::ActivateWindow(window.get());
+  const gfx::Rect shelf_widget_bounds =
+      GetShelfWidget()->GetWindowBoundsInScreen();
+  gfx::Point start = shelf_widget_bounds.bottom_center();
+  StartScroll(start);
+  const int shelf_size = ShelfConfig::Get()->shelf_size();
+  const int hotseat_size = ShelfConfig::Get()->hotseat_size();
+  const int hotseat_padding_size = ShelfConfig::Get()->hotseat_bottom_padding();
+  UpdateScroll(-shelf_size - hotseat_size - hotseat_padding_size);
+  const int hotseat_y =
+      GetShelfWidget()->hotseat_widget()->GetWindowBoundsInScreen().y();
+
+  // Drag down, the hotseat should not move because it was extended when the
+  // window drag began.
+  UpdateScroll(10);
+
+  EXPECT_EQ(hotseat_y,
+            GetShelfWidget()->hotseat_widget()->GetWindowBoundsInScreen().y());
+  EndScroll(/*is_fling=*/false, 0.f);
+}
+
+// Tests that dragging below the hotseat after dragging the MRU up results in
+// the hotseat not moving from its extended position with an autohidden shelf.
+TEST_F(ShelfLayoutManagerWindowDraggingTest,
+       DragBelowHotseatDoesNotMoveHotseatAutoHiddenShelf) {
+  // Extend the hotseat, then start dragging the window.
+  std::unique_ptr<aura::Window> window =
+      AshTestBase::CreateTestWindow(gfx::Rect(0, 0, 400, 400));
+  wm::ActivateWindow(window.get());
+  SwipeUpOnShelf();
+  const gfx::Rect shelf_widget_bounds =
+      GetShelfWidget()->GetWindowBoundsInScreen();
+  const gfx::Point start = shelf_widget_bounds.bottom_center();
+  StartScroll(start);
+  const int shelf_size = ShelfConfig::Get()->shelf_size();
+  const int hotseat_size = ShelfConfig::Get()->hotseat_size();
+  const int hotseat_padding_size = ShelfConfig::Get()->hotseat_bottom_padding();
+  UpdateScroll(-shelf_size - hotseat_size - hotseat_padding_size);
+  const int hotseat_y =
+      GetShelfWidget()->hotseat_widget()->GetWindowBoundsInScreen().y();
+
+  // Drag down, the hotseat should not move because it was extended when the
+  // window drag began.
+  UpdateScroll(10);
+
+  EXPECT_EQ(hotseat_y,
+            GetShelfWidget()->hotseat_widget()->GetWindowBoundsInScreen().y());
+  EndScroll(/*is_fling=*/false, 0.f);
+}
+
 TEST_F(ShelfLayoutManagerWindowDraggingTest, NoOpIfDragStartsAboveShelf) {
   std::unique_ptr<aura::Window> window =
       AshTestBase::CreateTestWindow(gfx::Rect(0, 0, 400, 400));