Changes the order of deleting child windows at shutdown.

Instead of simply deleting depth-first, it deletes all
toplevel windows first and then remove the containers.
This would be safer since all of the containers exist during deleting
the child windows.

This change would enable to eliminate other NULL checks in ash,
but it will be done in further CLs.

BUG=273310
R=derat@chromium.org, oshima@chromium.org
TEST=covered by the new test case

Review URL: https://chromiumcodereview.appspot.com/23219004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@218488 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 3 deletions

diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index dd23743..6e49c48 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -4,6 +4,7 @@
 
 #include "ash/root_window_controller.h"
 
+#include <queue>
 #include <vector>
 
 #include "ash/ash_constants.h"
@@ -44,11 +45,13 @@
 #include "base/command_line.h"
 #include "base/time/time.h"
 #include "ui/aura/client/aura_constants.h"
+#include "ui/aura/client/drag_drop_client.h"
 #include "ui/aura/client/tooltip_client.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/aura/window_observer.h"
+#include "ui/aura/window_tracker.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/models/menu_model.h"
 #include "ui/gfx/screen.h"
@@ -404,6 +407,8 @@ void RootWindowController::CloseChildWindows() {
     docked_layout_manager_ = NULL;
   }
 
+  aura::client::SetDragDropClient(root_window_.get(), NULL);
+
   // TODO(harrym): Remove when Status Area Widget is a child view.
   shelf_->ShutdownStatusAreaWidget();
 
@@ -417,10 +422,26 @@ void RootWindowController::CloseChildWindows() {
   workspace_controller_.reset();
   aura::client::SetTooltipClient(root_window_.get(), NULL);
 
-  while (!root_window_->children().empty()) {
-    aura::Window* child = root_window_->children()[0];
-    delete child;
+  // Remove all toplevel windows first.
+  std::queue<aura::Window*> non_toplevel_windows;
+  non_toplevel_windows.push(root_window_.get());
+  while (!non_toplevel_windows.empty()) {
+    aura::Window* non_toplevel_window = non_toplevel_windows.front();
+    non_toplevel_windows.pop();
+    aura::WindowTracker toplevel_windows;
+    for (size_t i = 0; i < non_toplevel_window->children().size(); ++i) {
+      aura::Window* child = non_toplevel_window->children()[i];
+      if (child->delegate())
+        toplevel_windows.Add(child);
+      else
+        non_toplevel_windows.push(child);
+    }
+    while (!toplevel_windows.windows().empty())
+      delete *toplevel_windows.windows().begin();
   }
+  // And then remove the containers.
+  while (!root_window_->children().empty())
+    delete root_window_->children()[0];
 
   shelf_.reset(NULL);
 }