Avoids updating dock alignment when drag is cancelled

ash/wm/dock/docked_window_layout_manager.cc

Index: ash/wm/dock/docked_window_layout_manager.cc
diff --git a/ash/wm/dock/docked_window_layout_manager.cc b/ash/wm/dock/docked_window_layout_manager.cc
index fcbecfc00f4255e730db781b11349fae71853c1f..6538eacf5e4f040aae07747825f76424f2413b46 100644
--- a/ash/wm/dock/docked_window_layout_manager.cc
+++ b/ash/wm/dock/docked_window_layout_manager.cc
@@ -464,6 +464,13 @@ void DockedWindowLayoutManager::StartDragging(aura::Window* window) {
   if (dragged_window_->parent() != dock_container_) {
     dragged_window_->AddObserver(this);
     dragged_state->AddObserver(this);
+  } else if (!IsAnyWindowDocked() &&

[pkotwicz, 2014/01/17 00:12:18]

The reason that we check |DragDetails::bounds_change| is not obvious to me. Can
you please add a comment?

[varkha, 2014/01/17 01:05:28]

Done.

+             dragged_state->drag_details() &&
+             !(dragged_state->drag_details()->bounds_change &
+                 WindowResizer::kBoundsChange_Resizes)) {
+    // If there are no other docked windows clear alignment when a docked window
+    // is moved.
+    alignment_ = DOCKED_ALIGNMENT_NONE;
   }
   is_dragged_from_dock_ = window->parent() == dock_container_;
   DCHECK(!is_dragged_window_docked_);
@@ -509,15 +516,21 @@ void DockedWindowLayoutManager::FinishDragging(DockedAction action,
   DCHECK (!is_dragged_window_docked_);
   // Stop observing a window unless it is docked container's child in which
   // case it needs to keep being observed after the drag completes.
+  wm::WindowState* dragged_state = wm::GetWindowState(dragged_window_);

[pkotwicz, 2014/01/17 00:12:18]

Nit: Move initialization of |dragged_state| to line 522.

[varkha, 2014/01/17 01:05:28]

Done. No need to change this since it is only used once.

   if (dragged_window_->parent() != dock_container_) {
     dragged_window_->RemoveObserver(this);
-    wm::GetWindowState(dragged_window_)->RemoveObserver(this);
+    dragged_state->RemoveObserver(this);
     if (last_active_window_ == dragged_window_)
       last_active_window_ = NULL;
 
     views::corewm::SetWindowShowAnimationDuration(dragged_window_,
                                                   base::TimeDelta());
   } else {
+    // If this is the first window that got docked by a move - update alignment.

[pkotwicz, 2014/01/17 00:12:18]

Nit: No hyphen

[varkha, 2014/01/17 01:05:28]

Done.

+    if (alignment_ == DOCKED_ALIGNMENT_NONE) {
+      alignment_ = GetAlignmentOfWindow(dragged_window_);
+      DCHECK(alignment_ != DOCKED_ALIGNMENT_NONE);

[pkotwicz, 2014/01/17 00:12:18]

Nit: DCHECK_NE

[pkotwicz, 2014/01/17 00:50:45]

The DCHECK() can fail when FinishDragging() is called from OnWindowDestroying().
(That seems to be the source of unit test failures). 

[varkha, 2014/01/17 01:05:28]

Done. When window is destroyed while it is being dragged the action should be
set to NONE.

+    }
     // A window is no longer dragged and is a child.
     // When a window becomes a child at drag start this is
     // the only opportunity we will have to enforce a window
@@ -985,25 +998,9 @@ void DockedWindowLayoutManager::UpdateDockedWidth(int width) {
 void DockedWindowLayoutManager::OnDraggedWindowDocked(aura::Window* window) {
   DCHECK(!is_dragged_window_docked_);
   is_dragged_window_docked_ = true;
-
-  // If there are no other docked windows update alignment when the window is
-  // moved.
-  if (!IsAnyWindowDocked() &&
-      wm::GetWindowState(dragged_window_)->drag_details() &&
-      !(wm::GetWindowState(dragged_window_)->drag_details()->bounds_change &
-          WindowResizer::kBoundsChange_Resizes)) {
-    alignment_ = DOCKED_ALIGNMENT_NONE;
-  }
 }
 
 void DockedWindowLayoutManager::OnDraggedWindowUndocked() {
-  // If this is the first window getting docked by moving it - update alignment.
-  if (!IsAnyWindowDocked() &&
-      wm::GetWindowState(dragged_window_)->drag_details() &&
-      !(wm::GetWindowState(dragged_window_)->drag_details()->bounds_change &
-          WindowResizer::kBoundsChange_Resizes)) {
-    alignment_ = GetAlignmentOfWindow(dragged_window_);
-  }
   DCHECK (is_dragged_window_docked_);
   is_dragged_window_docked_ = false;
 }