Fix dock mode with 2+ external displays.

ui/display/chromeos/display_configurator.cc

 // Copyright 2014 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 "ui/display/chromeos/display_configurator.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 285 matching lines @@
 
       for (size_t i = 0; i < states.size(); ++i) {
         const DisplayState* state = &states[i];
         (*requests)[i].mode = display_power[i] ? state->mirror_mode : NULL;
       }
       break;
     }
     case MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED:
     case MULTIPLE_DISPLAY_STATE_MULTI_EXTENDED: {
       if ((new_display_state == MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED &&
-           states.size() != 2) ||
+           states.size() != 2 && num_on_displays != 2) ||
           (new_display_state == MULTIPLE_DISPLAY_STATE_MULTI_EXTENDED &&
-           states.size() <= 2) ||
-          (num_on_displays != 0 &&
-           num_on_displays != static_cast<int>(displays.size()))) {
+           num_on_displays <= 2)) {
         LOG(WARNING) << "Ignoring request to enter extended mode with "
                      << states.size() << " connected display(s) and "
                      << num_on_displays << " turned on";
         return false;
       }
 
       for (size_t i = 0; i < states.size(); ++i) {
         const DisplayState* state = &states[i];
         (*requests)[i].origin.set_y(size.height() ? size.height() + kVerticalGap
                                                   : 0);
@@ skipping 815 matching lines @@
 
   int64_t max_display_id = 0;
   for (const auto& display : virtual_display_snapshots_)
     max_display_id = std::max(max_display_id, display->display_id());
   last_virtual_display_id_ = max_display_id & 0xff;
 
   return true;
 }
 
 }  // namespace ui