Refactor intra-strip panel drags by introducing PanelDragController.

chrome/browser/ui/panels/panel_drag_controller.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/ui/panels/panel_drag_controller.h"
+
+#include "base/logging.h"
+#include "chrome/browser/ui/panels/panel.h"
+#include "chrome/browser/ui/panels/panel_strip.h"
+
+PanelDragController::PanelDragController()
+    : dragging_panel_(NULL) {
+}
+
+PanelDragController::~PanelDragController() {
+  DCHECK(panels_pending_to_remove_.empty());
+}
+
+void PanelDragController::StartDragging(Panel* panel) {
+  DCHECK(!dragging_panel_);

[jennb, 2012/02/17 21:28:45]

Also DCHECK panel->panel_strip()->CanDragPanel(panel)?

[jianli, 2012/02/17 23:52:56]

Done.

+
+  dragging_panel_ = panel;
+  dragging_panel_->panel_strip()->StartDraggingPanel(panel);
+}
+
+void PanelDragController::Drag(int delta_x, int delta_y) {
+  DCHECK(dragging_panel_);
+
+  dragging_panel_->panel_strip()->DragPanel(delta_x, delta_y);
+}
+
+void PanelDragController::EndDragging(bool cancelled) {
+  DCHECK(dragging_panel_);
+
+  dragging_panel_->panel_strip()->EndDraggingPanel(cancelled);
+  dragging_panel_ = NULL;
+
+  DelayedRemove();
+}
+
+bool PanelDragController::CanRemovePanel(Panel* panel) {
+  if (!dragging_panel_)
+    return true;
+
+  // The following panels can't be removed immediately:
+  // 1) The dragging panel no matter which strip it is in.
+  // 2) All docked panels.
+  bool can_remove = (panel != dragging_panel_) &&

[jennb, 2012/02/17 21:28:45]

if (panel == dragging_panel_ || is_a_docked_panel)
   put in pending list
   return false

return true

[jianli, 2012/02/17 23:52:56]

Done.

+                    (panel->panel_strip()->type() != PanelStrip::DOCKED);
+  if (!can_remove)
+    panels_pending_to_remove_.insert(panel);
+
+  return can_remove;
+}
+
+void PanelDragController::DelayedRemove() {
+  for (std::set<Panel*>::const_iterator iter =
+           panels_pending_to_remove_.begin();
+       iter != panels_pending_to_remove_.end(); ++iter) {
+    (*iter)->Close();

[jennb, 2012/02/17 21:28:45]

The existing logic allows Close() while dragging. Only the remove() part is
delayed. Is it really necessary to change the existing design? After all,
Close() might not actually close a window.

[jianli, 2012/02/17 23:52:56]

Per discussion, I remove it from this patch.

+  }
+
+  panels_pending_to_remove_.clear();
+}