Treats empty layout as expected.

chrome/common/extensions/extension_manifest_constants.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 "chrome/common/extensions/extension_manifest_constants.h"
 
 namespace extension_manifest_keys {
 
 const char kAllFrames[] = "all_frames";
 const char kAltKey[] = "altKey";
@@ skipping 313 matching lines @@
     "Invalid value for 'incognito'.";
 const char kInvalidIncognitoModeForPlatformApp[] =
     "Invalid value for 'incognito'. Packaged apps must use split incognito "
     "mode.";
 const char kInvalidInputComponents[] =
     "Invalid value for 'input_components'";
 const char kInvalidInputComponentDescription[] =
     "Invalid value for 'input_components[*].description";
 const char kInvalidInputComponentLayoutName[] =
     "Invalid value for 'input_components[*].layouts[*]";
-const char kInvalidInputComponentLayouts[] =
-    "Invalid value for 'input_components[*].layouts";
 const char kInvalidInputComponentName[] =
     "Invalid value for 'input_components[*].name";
 const char kInvalidInputComponentShortcutKey[] =
     "Invalid value for 'input_components[*].shortcutKey";
 const char kInvalidInputComponentShortcutKeycode[] =
     "Invalid value for 'input_components[*].shortcutKey.keyCode";
 const char kInvalidInputComponentType[] =
     "Invalid value for 'input_components[*].type";
 const char kInvalidIntent[] =
     "Invalid value for intents[*]";
@@ skipping 260 matching lines @@
 const char kScriptBadgeTitleIgnored[] =
     "default_title specified in script_badge manifest section will not be "
     "used.";
 const char kWebRequestConflictsWithLazyBackground[] =
     "The 'webRequest' API cannot be used with event pages.";
 #if defined(OS_CHROMEOS)
 const char kIllegalPlugins[] =
     "Extensions cannot install plugins on Chrome OS";
 #endif
 }  // namespace extension_manifest_errors