Add support for an optional "requirements" section in extension/app manifests.

chrome/common/extensions/extension_constants.cc

 // Copyright (c) 2011 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"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/string_util.h"
@@ skipping 62 matching lines @@
 const char* kPageActionId = "id";
 const char* kPageActionPopup = "popup";
 const char* kPageActionPopupHeight = "height";
 const char* kPageActionPopupPath = "path";
 const char* kPageActions = "page_actions";
 const char* kPermissions = "permissions";
 const char* kPlugins = "plugins";
 const char* kPluginsPath = "path";
 const char* kPluginsPublic = "public";
 const char* kPublicKey = "key";
+const char* kRequirements = "requirements";
 const char* kRunAt = "run_at";
 const char* kShiftKey = "shiftKey";
 const char* kShortcutKey = "shortcutKey";
 const char* kSidebar = "sidebar";
 const char* kSidebarDefaultIcon = "default_icon";
 const char* kSidebarDefaultPage = "default_page";
 const char* kSidebarDefaultTitle = "default_title";
 const char* kSignature = "signature";
 const char* kTheme = "theme";
 const char* kThemeColors = "colors";
@@ skipping 238 matching lines @@
 const char* kInvalidPermissions =
     "Required value 'permissions' is missing or invalid.";
 const char* kInvalidPermissionScheme =
     "Invalid scheme for 'permissions[*]'.";
 const char* kInvalidPlugins =
     "Invalid value for 'plugins'.";
 const char* kInvalidPluginsPath =
     "Invalid value for 'plugins[*].path'.";
 const char* kInvalidPluginsPublic =
     "Invalid value for 'plugins[*].public'.";
+const char* kInvalidRequirement =
+    "Invalid value for requirement \"*\"";
+const char* kInvalidRequirements =
+    "Invalid value for 'requirements'";
 const char* kInvalidRunAt =
     "Invalid value for 'content_scripts[*].run_at'.";
 const char* kInvalidSidebar =
     "Invalid value for 'sidebar'.";
 const char* kInvalidSidebarDefaultIconPath =
     "Invalid value for 'sidebar.default_icon'.";
 const char* kInvalidSidebarDefaultPage =
     "Invalid value for 'sidebar.default_page'.";
 const char* kInvalidSidebarDefaultTitle =
     "Invalid value for 'sidebar.default_title'.";
@@ skipping 149 matching lines @@
 const char* kCloudPrintAppId = "mfehgcgbbipciphmccgaenjidiccnmng";
 const char* kAppsPromoHistogram = "Extensions.AppsPromo";
 const char* kAppLaunchHistogram = "Extensions.AppLaunch";
 #if defined(OS_CHROMEOS)
 const char* kAccessExtensionPath =
     "/usr/share/chromeos-assets/accessibility/extensions";
 const char* kChromeVoxDirectoryName = "access_chromevox";
 #endif
 
 }