Move window finalization handling logic to the same function.

Currently when swiping up from bottom to drag a window, the window can
be ended in 4 different places: restore to its old position, go to home
screen, drop in overview, or snap in splitview. These operations are
handled in different places, with the first 2 handled in
FinalizedDraggedWindow() function and the latter 2 handled in
EndDrag() function. The reason for it to avoid window state change to
interfere with shelf state change, see https://crrev.com/c/2004052.

This CL moves the logic of window finalization operations together while
keeping the existing logic unchanged.

This CL doesn't have any functional change.

Bug: None
Change-Id: Ib2c4e866893c51ee952725a3b80c701f8b02120a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2320770Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792108}

ash/home_screen/drag_window_from_shelf_controller.cc

@@ -240,6 +240,7 @@ base::Optional<ShelfWindowDragResult> DragWindowFromShelfController::EndDrag(
     return base::nullopt;
 
   drag_started_ = false;
+  previous_location_in_screen_ = location_in_screen;
   presentation_time_recorder_.reset();
   OverviewController* overview_controller = Shell::Get()->overview_controller();
   SplitViewController* split_view_controller =
@@ -248,8 +249,7 @@ base::Optional<ShelfWindowDragResult> DragWindowFromShelfController::EndDrag(
   const bool in_splitview = split_view_controller->InSplitViewMode();
   const bool drop_window_in_overview =
       ShouldDropWindowInOverview(location_in_screen, velocity_y);
-  SplitViewController::SnapPosition snap_position =
-      GetSnapPositionOnDragEnd(location_in_screen, velocity_y);
+  end_snap_position_ = GetSnapPositionOnDragEnd(location_in_screen, velocity_y);
 
   window_drag_result_ = base::nullopt;
   if (ShouldGoToHomeScreen(location_in_screen, velocity_y)) {
@@ -266,19 +266,18 @@ base::Optional<ShelfWindowDragResult> DragWindowFromShelfController::EndDrag(
   } else {
     if (drop_window_in_overview)
       window_drag_result_ = ShelfWindowDragResult::kGoToOverviewMode;
-    else if (snap_position != SplitViewController::NONE)
+    else if (end_snap_position_ != SplitViewController::NONE)
       window_drag_result_ = ShelfWindowDragResult::kGoToSplitviewMode;
     // For window that may drop in overview or snap in split screen, restore its
     // original backdrop mode.
     WindowBackdrop::Get(window_)->RestoreBackdrop();
   }
+  WindowState::Get(window_)->DeleteDragDetails();
 
   if (window_drag_result_.has_value()) {
     UMA_HISTOGRAM_ENUMERATION(kHandleDragWindowFromShelfHistogramName,
                               *window_drag_result_);
   }
-
-  OnDragEnded(location_in_screen, drop_window_in_overview, snap_position);
   return window_drag_result_;
 }
 
@@ -301,9 +300,11 @@ void DragWindowFromShelfController::CancelDrag() {
     overview_controller->EndOverview(OverviewEnterExitType::kImmediateExit);
   ReshowHiddenWindowsOnDragEnd();
 
+  window_drag_result_ = ShelfWindowDragResult::kDragCanceled;
   OnDragEnded(previous_location_in_screen_,
               /*should_drop_window_in_overview=*/false,
               /*snap_position=*/SplitViewController::NONE);
+  WindowState::Get(window_)->DeleteDragDetails();
 }
 
 bool DragWindowFromShelfController::IsDraggedWindowAnimating() const {
@@ -319,22 +320,9 @@ void DragWindowFromShelfController::FinalizeDraggedWindow() {
   DCHECK(!drag_started_);
   DCHECK(window_);
 
-  switch (*window_drag_result_) {
-    case ShelfWindowDragResult::kGoToHomeScreen:
-      ScaleDownWindowAfterDrag();
-      break;
-    case ShelfWindowDragResult::kRestoreToOriginalBounds:
-      ScaleUpToRestoreWindowAfterDrag();
-      break;
-    case ShelfWindowDragResult::kGoToOverviewMode:
-    case ShelfWindowDragResult::kGoToSplitviewMode:
-    case ShelfWindowDragResult::kDragCanceled:
-      // No action is needed.
-      break;
-  }
-
-  window_drag_result_.reset();
-  started_in_overview_ = false;
+  OnDragEnded(previous_location_in_screen_,
+              *window_drag_result_ == ShelfWindowDragResult::kGoToOverviewMode,
+              end_snap_position_);
 }
 
 void DragWindowFromShelfController::OnWindowDestroying(aura::Window* window) {
@@ -425,7 +413,22 @@ void DragWindowFromShelfController::OnDragEnded(
         ->SetWallpaperProperty(wallpaper_constants::kClear);
   }
 
-  WindowState::Get(window_)->DeleteDragDetails();
+  DCHECK(window_drag_result_.has_value());
+  switch (*window_drag_result_) {
+    case ShelfWindowDragResult::kGoToHomeScreen:
+      ScaleDownWindowAfterDrag();
+      break;
+    case ShelfWindowDragResult::kRestoreToOriginalBounds:
+      ScaleUpToRestoreWindowAfterDrag();
+      break;
+    case ShelfWindowDragResult::kGoToOverviewMode:
+    case ShelfWindowDragResult::kGoToSplitviewMode:
+    case ShelfWindowDragResult::kDragCanceled:
+      // No action is needed.
+      break;
+  }
+  window_drag_result_.reset();
+  started_in_overview_ = false;
 }
 
 void DragWindowFromShelfController::UpdateDraggedWindow(

ash/home_screen/drag_window_from_shelf_controller.h

@@ -205,6 +205,9 @@ class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
 
   bool during_window_restoration_callback_ = false;
 
+  SplitViewController::SnapPosition end_snap_position_ =
+      SplitViewController::NONE;
+
   std::unique_ptr<PresentationTimeRecorder> presentation_time_recorder_;
 
   base::WeakPtrFactory<DragWindowFromShelfController> weak_ptr_factory_{this};

ash/shelf/shelf_layout_manager.cc

@@ -2399,11 +2399,6 @@ void ShelfLayoutManager::CompleteDrag(const ui::LocatedEvent& event_in_screen) {
   else
     CancelDrag(window_drag_result);
 
-  // Dragged window is finalized after drag handling is completed so drag state
-  // does not interfere with updates on shelf state during window state changes.
-  if (window_drag_controller_.get())
-    window_drag_controller_->FinalizeDraggedWindow();
-
   // Hotseat gestures are meaningful only in tablet mode with hotseat enabled.
   if (chromeos::switches::ShouldShowShelfHotseat() &&
       Shell::Get()->IsInTabletMode()) {
@@ -2464,12 +2459,21 @@ void ShelfLayoutManager::CancelDrag(
     else
       Shell::Get()->app_list_controller()->DismissAppList();
   } else {
-    MaybeCancelWindowDrag();
     // Set |drag_status_| to kDragCancelInProgress to set the
     // auto hide state to |drag_auto_hide_state_|, which is the
     // visibility state before starting drag.
     drag_status_ = kDragCancelInProgress;
     UpdateVisibilityState();
+
+    // Dragged window is finalized after drag handling is completed so drag
+    // state does not interfere with updates on shelf state during window state
+    // changes.
+    if (window_drag_controller_.get()) {
+      if (window_drag_result.has_value())
+        window_drag_controller_->FinalizeDraggedWindow();
+      else
+        MaybeCancelWindowDrag();
+    }
   }
   if (hotseat_is_in_drag_) {
     // If the gesture started the overview session, the hotseat will be
@@ -2509,6 +2513,12 @@ void ShelfLayoutManager::CompleteDragWithChangedVisibility() {
   drag_status_ = kDragCompleteInProgress;
 
   UpdateVisibilityState();
+
+  // Dragged window is finalized after drag handling is completed so drag state
+  // does not interfere with updates on shelf state during window state changes.
+  if (window_drag_controller_.get())
+    window_drag_controller_->FinalizeDraggedWindow();
+
   drag_status_ = kDragNone;
   if (hotseat_is_in_drag_)
     hotseat_presentation_time_recorder_.reset();