Make dragging outside the app list scroll back to its original position.

ui/app_list/views/apps_grid_view.cc

Index: ui/app_list/views/apps_grid_view.cc
diff --git a/ui/app_list/views/apps_grid_view.cc b/ui/app_list/views/apps_grid_view.cc
index a465cdc2e8b08e054a417c79a64ada69d437e87e..2f7c23650835bceaebe14378c307d75f5c086adc 100644
--- a/ui/app_list/views/apps_grid_view.cc
+++ b/ui/app_list/views/apps_grid_view.cc
@@ -183,10 +183,6 @@ class SynchronousDrag : public ui::DragSourceWin {
   virtual void OnDragSourceMove() OVERRIDE {
     grid_view_->UpdateDrag(app_list::AppsGridView::MOUSE,
                            GetCursorInGridViewCoords());
-
-    // Don't turn pages if the cursor is dragged outside the view.
-    if (!IsCursorWithinGridView())
-      grid_view_->StopPageFlipTimer();
   }
 
   void SetupExchangeData(ui::OSExchangeData* data) {
@@ -244,6 +240,7 @@ AppsGridView::AppsGridView(AppsGridViewDelegate* delegate,
       drag_pointer_(NONE),
       drag_and_drop_host_(NULL),
       forward_events_to_drag_and_drop_host_(false),
+      drag_start_page_(-1),
       page_flip_target_(-1),
       page_flip_delay_in_ms_(kPageFlipDelayInMs),
       bounds_animator_(this) {
@@ -323,6 +320,7 @@ void AppsGridView::InitiateDrag(AppListItemView* view,
 
   drag_view_ = view;
   drag_view_offset_ = event.location();
+  drag_start_page_ = pagination_model_->selected_page();
   ExtractDragLocation(event, &drag_start_grid_view_);
   drag_view_start_ = gfx::Point(drag_view_->x(), drag_view_->y());
 }
@@ -448,6 +446,9 @@ void AppsGridView::EndDrag(bool cancel) {
   drag_pointer_ = NONE;
   drop_target_ = Index();
   drag_view_ = NULL;
+  drag_start_grid_view_ = gfx::Point();
+  drag_start_page_ = -1;
+  drag_view_offset_ = gfx::Point();
   AnimateToIdealBounds();
 
   StopPageFlipTimer();
@@ -898,11 +899,16 @@ void AppsGridView::ExtractDragLocation(const ui::LocatedEvent& event,
 
 void AppsGridView::CalculateDropTarget(const gfx::Point& drag_point,
                                        bool use_page_button_hovering) {
-  const int current_page = pagination_model_->selected_page();
+  int current_page = pagination_model_->selected_page();
+  gfx::Point point(drag_point);
+  if (!HitTestPoint(drag_point)) {
+    point = drag_start_grid_view_;
+    current_page = drag_start_page_;
+  }
 
   if (use_page_button_hovering &&
-      page_switcher_view_->bounds().Contains(drag_point)) {
-    gfx::Point page_switcher_point(drag_point);
+      page_switcher_view_->bounds().Contains(point)) {
+    gfx::Point page_switcher_point(point);
     views::View::ConvertPointToTarget(this, page_switcher_view_,
                                       &page_switcher_point);
     int page = page_switcher_view_->GetPageForPoint(page_switcher_point);
@@ -911,9 +917,9 @@ void AppsGridView::CalculateDropTarget(const gfx::Point& drag_point,
       drop_target_.slot = tiles_per_page() - 1;
     }
   } else {
-    const int drop_row = drag_point.y() / kPreferredTileHeight;
+    const int drop_row = point.y() / kPreferredTileHeight;
     const int drop_col = std::min(cols_ - 1,
-                                  drag_point.x() / kPreferredTileWidth);
+                                  point.x() / kPreferredTileWidth);
 
     drop_target_.page = current_page;
     drop_target_.slot = std::max(0, std::min(
@@ -990,6 +996,8 @@ void AppsGridView::DispatchDragEventToDragAndDropHost(
 }
 
 void AppsGridView::MaybeStartPageFlipTimer(const gfx::Point& drag_point) {
+  if (!HitTestPoint(drag_point))
+    StopPageFlipTimer();
   int new_page_flip_target = -1;
 
   if (page_switcher_view_->bounds().Contains(drag_point)) {
@@ -1013,8 +1021,8 @@ void AppsGridView::MaybeStartPageFlipTimer(const gfx::Point& drag_point) {
     return;
 
   if (pagination_model_->is_valid_page(new_page_flip_target)) {
+    StopPageFlipTimer();
     page_flip_target_ = new_page_flip_target;
-    page_flip_timer_.Stop();
 
     if (page_flip_target_ != pagination_model_->selected_page()) {
       page_flip_timer_.Start(FROM_HERE,
@@ -1022,8 +1030,7 @@ void AppsGridView::MaybeStartPageFlipTimer(const gfx::Point& drag_point) {
           this, &AppsGridView::OnPageFlipTimer);
     }
   } else {
-    page_flip_target_ = -1;
-    page_flip_timer_.Stop();
+    StopPageFlipTimer();

[xiyuan, 2013/07/19 04:36:46]

nit: We probably could move this to be before the "if" since we are doing it in
both branches now.

[koz (OOO until 15th September), 2013/07/19 08:00:32]

Done.

   }
 }