Don't assume gfx::Screen::GetNumDisplays() == GetAllDisplays().size().

extensions/browser/api/system_display/display_info_provider.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 "extensions/browser/api/system_display/display_info_provider.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "extensions/common/api/system_display.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
@@ skipping 62 matching lines @@
   DCHECK(display_info_provider);
   g_display_info_provider = display_info_provider;
 }
 
 DisplayInfo DisplayInfoProvider::GetAllDisplaysInfo() {
   // TODO(scottmg): Native is wrong http://crbug.com/133312
   gfx::Screen* screen = gfx::Screen::GetNativeScreen();
   int64 primary_id = screen->GetPrimaryDisplay().id();
   std::vector<gfx::Display> displays = screen->GetAllDisplays();
   DisplayInfo all_displays;
-  for (int i = 0; i < screen->GetNumDisplays(); ++i) {
+  for (const gfx::Display& display : displays) {
     linked_ptr<core_api::system_display::DisplayUnitInfo> unit(
-        CreateDisplayUnitInfo(displays[i], primary_id));
-    UpdateDisplayUnitInfoForPlatform(displays[i], unit.get());
+        CreateDisplayUnitInfo(display, primary_id));
+    UpdateDisplayUnitInfoForPlatform(display, unit.get());
     all_displays.push_back(unit);
   }
   return all_displays;
 }
 
 DisplayInfoProvider::DisplayInfoProvider() {
 }
 
 }  // namespace extensions