Disable extended desktop.

ui/aura/display_change_observer_x11.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 "ui/aura/display_change_observer_x11.h"
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 112 matching lines @@
                          screen_resources->outputs[o]);
     if (output_info->connection != RR_Connected) {
       XRRFreeOutputInfo(output_info);
       continue;
     }
     XRRCrtcInfo* crtc_info = crtc_info_map[output_info->crtc];
     if (!crtc_info) {
       LOG(WARNING) << "Crtc not found for output: output=" << o;
       continue;
     }
+    // TODO(oshima): Temporarily ignore all displays other than
+    // primary, which has y = 0 to disable extended desktop.
+    // crbug.com/152003.
+    if (crtc_info->y != 0)
+      continue;
+
     XRRModeInfo* mode = FindMode(screen_resources, crtc_info->mode);
     if (!mode) {
       LOG(WARNING) << "Could not find a mode for the output: output=" << o;
       continue;
     }
     // Mirrored monitors have the same y coordinates.
     if (y_coords.find(crtc_info->y) != y_coords.end())
       continue;
     displays.push_back(gfx::Display());
 
@@ skipping 15 matching lines @@
       // fails.
       int64 new_id = gfx::Display::GetID(manufacturer_id, serial_number);
       if (ids.find(new_id) == ids.end()) {
         displays.back().set_id(new_id);
         ids.insert(new_id);
       }
     }
 
     y_coords.insert(crtc_info->y);
     XRRFreeOutputInfo(output_info);
+
+    // TODO(oshima): There is only one display in m23.
+    // Set the id to 0. crbug.com/152003.
+    displays.back().set_id(0);
   }
 
   // Free all allocated resources.
   for (std::map<XID, XRRCrtcInfo*>::const_iterator iter = crtc_info_map.begin();
        iter != crtc_info_map.end(); ++iter) {
     XRRFreeCrtcInfo(iter->second);
   }
   XRRFreeScreenResources(screen_resources);
 
   // PowerManager lays out the outputs vertically. Sort them by Y
   // coordinates.
   std::sort(displays.begin(), displays.end(), CompareDisplayY);
   int64 id = 0;
   for (std::vector<gfx::Display>::iterator iter = displays.begin();
        iter != displays.end(); ++iter) {
     if (iter->id() == gfx::Display::kInvalidDisplayID) {
       iter->set_id(id);
       ++id;
     }
   }
 
   Env::GetInstance()->display_manager()->OnNativeDisplaysChanged(displays);
 }
 
 }  // namespace internal
 }  // namespace aura