Made the EndDrag logic clearer by using |drag_view_| as Drag state.

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 f825000b4f262642be76a8c229383070835eaadd..80675ce1c2d09adc4462b6b35b27eff1717d714d 100644
--- a/ui/app_list/views/apps_grid_view.cc
+++ b/ui/app_list/views/apps_grid_view.cc
@@ -192,7 +192,7 @@ void AppsGridView::EnsureViewVisible(const views::View* view) {
 void AppsGridView::InitiateDrag(AppListItemView* view,
                                 Pointer pointer,
                                 const ui::LocatedEvent& event) {
-  if (drag_view_ || pulsing_blocks_model_.view_size())
+  if (drag_view_ || pulsing_blocks_model_.view_size() || !view)

[xiyuan, 2013/06/03 18:03:34]

nit: DCHECK(view) to catch the error as well since this should never happen and
should be fixed if it does happen.

[Mr4D (OOO till 08-26), 2013/06/03 18:35:16]

Done.

     return;
 
   drag_view_ = view;
@@ -222,8 +222,11 @@ void AppsGridView::InitiateDrag(AppListItemView* view,
 void AppsGridView::UpdateDrag(AppListItemView* view,
                               Pointer pointer,
                               const ui::LocatedEvent& event) {
-  if (!dragging() && drag_view_ &&
-      ExceededDragThreshold(event.location() - drag_start_)) {
+  // EndDrag was called before if |drag_view_| is NULL.
+  if (!drag_view_)
+    return;
+
+  if (!dragging() && ExceededDragThreshold(event.location() - drag_start_)) {
     drag_pointer_ = pointer;
     // Move the view to the front so that it appears on top of other views.
     ReorderChildView(drag_view_, -1);
@@ -258,10 +261,14 @@ void AppsGridView::UpdateDrag(AppListItemView* view,
 }
 
 void AppsGridView::EndDrag(bool cancel) {
+  // EndDrag was called before if |drag_view_| is NULL.
+  if (!drag_view_)
+    return;
+
   if (forward_events_to_drag_and_drop_host_) {
     forward_events_to_drag_and_drop_host_ = false;
     drag_and_drop_host_->EndDrag(cancel);
-  } else if (!cancel && dragging() && drag_view_) {
+  } else if (!cancel && dragging()) {
     CalculateDropTarget(last_drag_point_, true);
     if (IsValidIndex(drop_target_))
       MoveItemInModel(drag_view_, drop_target_);
@@ -276,10 +283,8 @@ void AppsGridView::EndDrag(bool cancel) {
 
   drag_pointer_ = NONE;
   drop_target_ = Index();
-  if (drag_view_) {
-    drag_view_ = NULL;
-    AnimateToIdealBounds();
-  }
+  drag_view_ = NULL;
+  AnimateToIdealBounds();
 
   page_flip_timer_.Stop();
   page_flip_target_ = -1;