Pressing tab in overview should cycle windows.

ash/wm/overview/window_selector.cc

 // Copyright 2013 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 "ash/wm/overview/window_selector.h"
 
 #include <algorithm>
 
 #include "ash/accessibility_delegate.h"
 #include "ash/ash_switches.h"
@@ skipping 284 matching lines @@
       break;
     case ui::VKEY_UP:
       num_key_presses_++;
       Move(WindowSelector::UP, true);
       break;
     case ui::VKEY_DOWN:
       num_key_presses_++;
       Move(WindowSelector::DOWN, true);
       break;
     case ui::VKEY_RIGHT:
+    case ui::VKEY_TAB:
       num_key_presses_++;
       Move(WindowSelector::RIGHT, true);
       break;
     case ui::VKEY_LEFT:
       num_key_presses_++;
       Move(WindowSelector::LEFT, true);
       break;
     case ui::VKEY_RETURN:
       // Ignore if no item is selected.
       if (!grid_list_[selected_grid_index_]->is_selecting())
@@ skipping 192 matching lines @@
   for (size_t i = 0;
       i <= grid_list_.size() &&
       grid_list_[selected_grid_index_]->Move(direction, animate); i++) {
     // TODO(flackr): If there are more than two monitors, move between grids
     // in the requested direction.
     selected_grid_index_ = (selected_grid_index_ + 1) % grid_list_.size();
   }
 }
 
 }  // namespace ash