Fix app list drag view being hidden on reparent when synchronous drag is setting up.

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 d3857553c2bdc1aa6fe2da271c795393a5a0f30f..a9116d15b21fbc42373927a39466c0a9790acd15 100644
--- a/ui/app_list/views/apps_grid_view.cc
+++ b/ui/app_list/views/apps_grid_view.cc
@@ -217,6 +217,8 @@ class SynchronousDrag : public ui::DragSourceWin {
     shortcut_path_ = shortcut_path;
   }
 
+  bool running() { return running_; }
+
   bool CanRun() {
     return has_shortcut_path_ && !running_;
   }
@@ -491,10 +493,20 @@ void AppsGridView::StartSettingUpSynchronousDrag() {
 
 bool AppsGridView::RunSynchronousDrag() {
 #if defined(OS_WIN)
-  if (synchronous_drag_ && synchronous_drag_->CanRun()) {
+  if (!synchronous_drag_)
+    return false;
+
+  if (synchronous_drag_->CanRun()) {
+    if (IsDraggingForReparentInHiddenGridView())
+      folder_delegate_->SetRootLevelDragViewVisible(false);
     synchronous_drag_->Run();
     synchronous_drag_ = NULL;
     return true;
+  } else if (!synchronous_drag_->running()) {

[tapted, 2014/05/02 01:52:47]

nit: I think the condition is redundant (i.e. can just be else {)

That is, because the Run() above would immediately run it, there's never a state
where running is true and CanRun is false.

(running && !CanRun)
  ==> (running && !(has_shortcut_path_ && !running_)
  ==> (running && (!has_shortcut_path  || running)
  ==> (running && !has_shortcut_path)
  ==> (has_shortcut_path && !has_shortcut_path)

(because running ==> CanRun was true at least once, requiring has_shortcut_path
to be true)

So paradox means !canrun ==> !running so this `if` is always true.

But my brain hurts now

[calamity, 2014/05/02 04:28:38]

Ah, true.

+    // The OS drag is not ready yet. If the root grid has a drag view because
+    // a reparent has started, ensure it is visible.
+    if (IsDraggingForReparentInHiddenGridView())
+      folder_delegate_->SetRootLevelDragViewVisible(true);
   }
 #endif
   return false;
@@ -766,6 +778,11 @@ void AppsGridView::ClearDragState(bool cancel_reparent) {
   dragging_for_reparent_item_ = false;
 }
 
+void AppsGridView::SetDragViewVisible(bool visible) {
+  DCHECK(drag_view_);
+  SetViewHidden(drag_view_, !visible, true);
+}
+
 void AppsGridView::SetDragAndDropHostOfCurrentAppList(
     ApplicationDragAndDropHost* drag_and_drop_host) {
   drag_and_drop_host_ = drag_and_drop_host;