Add test cases for panel overflow handling.

chrome/browser/ui/panels/panel_strip.cc

 // Copyright (c) 2011 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_strip.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 161 matching lines @@
   if (find(panels_.begin(), panels_.end(), panel) == panels_.end())
     return false;
 
   // If we're in the process of dragging, delay the removal.
   if (dragging_panel_index_ != kInvalidPanelIndex) {
     panels_pending_to_remove_.push_back(panel);
     return true;
   }
 
   DoRemove(panel);
-  Rearrange();
+
+  // Don't rearrange the strip if a panel is being moved from the panel strip
+  // to the overflow strip.
+  if (panel->expansion_state() != Panel::IN_OVERFLOW)
+    Rearrange();
+
   return true;
 }
 
 void PanelStrip::DelayedRemove() {
   for (size_t i = 0; i < panels_pending_to_remove_.size(); ++i)
     DoRemove(panels_pending_to_remove_[i]);
   panels_pending_to_remove_.clear();
   Rearrange();
 }
 
@@ skipping 482 matching lines @@
 
   // Start from the bottom to avoid reshuffling.
   for (Panels::reverse_iterator iter = panels_copy.rbegin();
        iter != panels_copy.rend(); ++iter)
     (*iter)->Close();
 }
 
 bool PanelStrip::is_dragging_panel() const {
   return dragging_panel_index_ != kInvalidPanelIndex;
 }