Move history API out of experimental. Allow extensions to override history page.

chrome/common/extensions/extension_constants.cc

 // Copyright (c) 2009 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_constants.h"
 
 namespace extension_manifest_keys {
 
 const wchar_t* kAllFrames = L"all_frames";
 const wchar_t* kBackground = L"background_page";
@@ skipping 172 matching lines @@
     "Required value 'version' is missing or invalid. It must be between 1-4 "
     "dot-separated integers each between 0 and 65536.";
 const char* kInvalidZipHash =
     "Required key 'zip_hash' is missing or invalid.";
 const char* kManifestParseError =
     "Manifest is not valid JSON.";
 const char* kManifestUnreadable =
     "Manifest file is missing or unreadable.";
 const char* kMissingFile =
     "At least one js or css file is required for 'content_scripts[*]'.";
+const char* kMultipleOverrides =
+    "An extension cannot override more than one page.";
 const char* kInvalidTheme =
     "Invalid value for 'theme'.";
 const char* kInvalidThemeImages =
     "Invalid value for theme images - images must be strings.";
 const char* kInvalidThemeImagesMissing =
     "Am image specified in the theme is missing.";
 const char* kInvalidThemeColors =
     "Invalid value for theme colors - colors must be integers";
 const char* kInvalidThemeTints =
     "Invalid value for theme images - tints must be decimal numbers.";
@@ skipping 38 matching lines @@
     "must be set to true in order to use any other web content features.";
 }  // namespace extension_manifest_errors
 
 namespace extension_urls {
 const char* kGalleryBrowsePrefix = "https://chrome.google.com/extensions";
 const char* kGalleryDownloadPrefix =
     "https://clients2.googleusercontent.com/crx/download";
 const char* kMiniGalleryBrowsePrefix = "https://tools.google.com/chrome/";
 const char* kMiniGalleryDownloadPrefix = "https://dl-ssl.google.com/chrome/";
 }