Fallback to use output_index when searching for internal display

ash/display/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 "ash/display/display_change_observer_x11.h"
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 101 matching lines @@
       XRRGetScreenResources(xdisplay_, x_root_window_);
   for (int output_index = 0; output_index < screen_resources->noutput;
        output_index++) {
     XID output = screen_resources->outputs[output_index];
     XRROutputInfo *output_info =
         XRRGetOutputInfo(xdisplay_, screen_resources, output);
     bool is_internal = chromeos::OutputConfigurator::IsInternalOutputName(
         std::string(output_info->name));
     XRRFreeOutputInfo(output_info);
     if (is_internal) {
-      // No need to check the return value of |GetDisplayID()| as
-      // the default value is |gfx::Display::kInvalidDisplayID| anyway.
-      gfx::Display::SetInternalDisplayId(GetDisplayId(output, output_index));
+      int64 id = GetDisplayId(output, output_index);
+      // Fallback to output index. crbug.com/180100
+      gfx::Display::SetInternalDisplayId(
+          id == gfx::Display::kInvalidDisplayID ? output_index : id);
       break;
     }
   }
   XRRFreeScreenResources(screen_resources);
 }
 
 DisplayChangeObserverX11::~DisplayChangeObserverX11() {
 }
 
 void DisplayChangeObserverX11::OnDisplayModeChanged() {
@@ skipping 82 matching lines @@
   // PowerManager lays out the outputs vertically. Sort them by Y
   // coordinates.
   std::sort(displays.begin(), displays.end(), CompareDisplayY);
 
   // DisplayManager can be null during the boot.
   Shell::GetInstance()->display_manager()->OnNativeDisplaysChanged(displays);
 }
 
 }  // namespace internal
 }  // namespace ash