Do not register invalid layout

ash/display/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 "ash/ash_switches.h"
 #include "ash/display/display_layout_store.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/display_util.h"
@@ skipping 50 matching lines @@
       layout->placement_list[0]->display_id ==
           gfx::Display::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())) << layout->ToString();
+  if (!DisplayLayout::Validate(list, *layout.get()))
+    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);
-  DCHECK(DisplayLayout::Validate(list, *layout)) << layout->ToString();
-  DCHECK_NE(layout->primary_id, gfx::Display::kInvalidDisplayID);
+  CHECK(DisplayLayout::Validate(list, *layout)) << layout->ToString();
+  CHECK_NE(layout->primary_id, gfx::Display::kInvalidDisplayID);

[oshima, 2016/03/31 01:15:44]

I'm adding CHECK to have better crash reports when this ever happens.

   return *layout;
 }
 
 void DisplayLayoutStore::UpdateMultiDisplayState(const DisplayIdList& list,
                                                  bool mirrored,
                                                  bool default_unified) {
   DCHECK(layouts_.find(list) != layouts_.end());
   if (layouts_.find(list) == layouts_.end())
     CreateDefaultDisplayLayout(list);
 
@@ skipping 13 matching lines @@
     placement->display_id = list[i + 1];
     placement->parent_display_id = list[i];
     layout->placement_list.push_back(std::move(placement));
   }
   layouts_[list] = std::move(layout);
   auto iter = layouts_.find(list);
   return iter->second.get();
 }
 
 }  // namespace ash