[ash] Don't remove an item when associated window is dragged

ash/shelf/shelf_window_watcher.cc

Index: ash/shelf/shelf_window_watcher.cc
diff --git a/ash/shelf/shelf_window_watcher.cc b/ash/shelf/shelf_window_watcher.cc
index b4e65e25a7b2f50761de5c0c524936e86163917c..964a867d9b8e05dce23d6fc83ef6e844a518c0a6 100644
--- a/ash/shelf/shelf_window_watcher.cc
+++ b/ash/shelf/shelf_window_watcher.cc
@@ -11,6 +11,7 @@
 #include "ash/shelf/shelf_window_watcher_item_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
+#include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/aura/client/activation_client.h"
@@ -40,6 +41,11 @@ bool HasLauncherItemForWindow(aura::Window* window) {
   return false;
 }
 
+// Returns true if |window| is in the process of being dragged.
+bool IsDragging(aura::Window* window) {
+  return ash::wm::GetWindowState(window)->is_dragged();
+}
+
 }  // namespace
 
 namespace ash {
@@ -146,7 +152,10 @@ void ShelfWindowWatcher::OnWindowActivated(aura::Window* gained_active,
 }
 
 void ShelfWindowWatcher::OnWindowAdded(aura::Window* window) {
-  observed_windows_.Add(window);
+  // |window| can be already observed after finishing the dragging of |window|.
+  if (!observed_windows_.IsObserving(window))
+    observed_windows_.Add(window);
+
   // Add LauncherItem if |window| already has a LauncherItemDetails when it is
   // created. Don't make a new LauncherItem for the re-parented |window| that
   // already has a LauncherItem.
@@ -156,7 +165,14 @@ void ShelfWindowWatcher::OnWindowAdded(aura::Window* window) {
 }
 
 void ShelfWindowWatcher::OnWillRemoveWindow(aura::Window* window) {
-  // Remove a child window of default container and its item if it has.
+  // When |window| is being dragged, its parent Window is changed from default
+  // container to docked container. To handle deleting a |window| during the
+  // dragging, it is not removed from observer here. In that case, |window| will
+  // be removed from observer and its item is removed at OnWindowDestroying().
+  if (HasLauncherItemForWindow(window) && IsDragging(window))
+    return;
+
+  // Remove a child window of default container.
   if (observed_windows_.IsObserving(window))
     observed_windows_.Remove(window);
 
@@ -164,10 +180,44 @@ void ShelfWindowWatcher::OnWillRemoveWindow(aura::Window* window) {
     RemoveLauncherItem(window);
 }
 
+void ShelfWindowWatcher::OnWindowParentChanged(aura::Window* window,
+                                               aura::Window* parent) {
+  if (!parent || !HasLauncherItemForWindow(window))
+    return;
+
+  aura::Window* root_window = window->GetRootWindow();
+  aura::Window* default_container = Shell::GetContainer(
+      root_window,
+      kShellWindowId_DefaultContainer);
+  aura::Window* docked_container = Shell::GetContainer(
+      root_window,
+      kShellWindowId_DockedContainer);
+
+  // When |parent| is |default_container|, this re-parenting is already handled
+  // by OnWindowAdded().
+  // When |parent| is |docked_container|, |window| is in the process of being
+  // dragged. This case is also already handled by OnWillRemoveWindow().
+  if (parent == default_container ||
+      (parent == docked_container && IsDragging(window)))

[sky, 2013/12/17 15:49:57]

Can you just check IsDragging here and not care about dock container?

+    return;
+
+  // Remove an item when |window|'s new parent is not a docked container or
+  // a default container.
+  observed_windows_.Remove(window);
+  RemoveLauncherItem(window);
+}
+
 void ShelfWindowWatcher::OnWindowDestroying(aura::Window* window) {
   // Remove the default container.
   if (observed_windows_.IsObserving(window))
     observed_windows_.Remove(window);
+
+  // Handle removing of |window| during its dragging. See the comment in
+  // OnWillRemoveWindow().
+  if (IsDragging(window)) {
+    DCHECK(HasLauncherItemForWindow(window));

[sky, 2013/12/17 15:49:57]

Why the DCHECK here?

+    RemoveLauncherItem(window);
+  }
 }
 
 void ShelfWindowWatcher::OnWindowPropertyChanged(aura::Window* window,