Improve error message for failing code insertion on about:-URLs

extensions/common/manifest_constants.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/common/manifest_constants.h"
 
 namespace extensions {
 
 namespace manifest_keys {
 
@@ skipping 232 matching lines @@
     "not been in invoked.";
 const char kAllURLOrActiveTabNeeded[] =
     "Either the '<all_urls>' or 'activeTab' permission is required.";
 const char kAppsNotEnabled[] =
     "Apps are not enabled.";
 const char kBackgroundPermissionNeeded[] =
     "Hosted apps that use 'background_page' must have the 'background' "
     "permission.";
 const char kBackgroundRequiredForPlatformApps[] =
     "Packaged apps must have a background page or background scripts.";
+const char kCannotAccessAboutUrl[] =
+    "Cannot access \"*\" at origin \"*\". Extension must have permission to "
+    "access the frame's origin, and matchAboutBlank must be true.";
 const char kCannotAccessChromeUrl[] = "Cannot access a chrome:// URL";
 const char kCannotAccessExtensionUrl[] =
     "Cannot access a chrome-extension:// URL of different extension";
 const char kCannotAccessPage[] =
     "Cannot access contents of url \"*\". "
     "Extension manifest must request permission to access this host.";
 const char kCannotChangeExtensionID[] =
     "Installed extensions cannot change their IDs.";
 const char kCannotClaimAllHostsInExtent[] =
     "Cannot claim all hosts ('*') in an extent.";
@@ skipping 427 matching lines @@
 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 manifest_errors
 
 }  // namespace extensions