Fix expected PlacementList sort order.

ui/display/manager/display_layout_store.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 <stdio.h>
 
 #include <string>
 #include <utility>
 
 #include "base/command_line.h"
@@ skipping 54 matching lines @@
   if (layout->placement_list.size() >= 1 &&
       layout->placement_list[0].display_id == kInvalidDisplayId) {
     if (layout->primary_id == list[1]) {
       layout->placement_list[0].display_id = list[0];
       layout->placement_list[0].parent_display_id = list[1];
     } else {
       layout->placement_list[0].display_id = list[1];
       layout->placement_list[0].parent_display_id = list[0];
     }
   }
-  DCHECK(DisplayLayout::Validate(list, *layout.get()))
-      << "ids=" << DisplayIdListToString(list)
-      << ", layout=" << layout->ToString();
+
+  if (!DisplayLayout::Validate(list, *layout.get())) {
+    NOTREACHED() << "Attempting to register an invalid layout: ids="
+                 << DisplayIdListToString(list)
+                 << ", layout=" << layout->ToString();
+    // We never allow to register an invalid layout, instead, we revert back to
+    // a default layout.
+    CreateDefaultDisplayLayout(list);
+    return;
+  }
+
   layouts_[list] = std::move(layout);
 }
 
 const DisplayLayout& DisplayLayoutStore::GetRegisteredDisplayLayout(
     const DisplayIdList& list) {
   DCHECK_NE(1u, list.size());
   const auto iter = layouts_.find(list);
   const DisplayLayout* layout = iter != layouts_.end()
                                     ? iter->second.get()
                                     : CreateDefaultDisplayLayout(list);
@@ skipping 24 matching lines @@
     placement.display_id = list[i + 1];
     placement.parent_display_id = list[i];
     layout->placement_list.push_back(placement);
   }
   layouts_[list] = std::move(layout);
   auto iter = layouts_.find(list);
   return iter->second.get();
 }
 
 }  // namespace display