Move kExtensionScheme from content to chrome

chrome/common/url_constants.h

 // 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.
 
 // Contains constants for known URLs and portions thereof.
 
 #ifndef CHROME_COMMON_URL_CONSTANTS_H_
 #define CHROME_COMMON_URL_CONSTANTS_H_
 #pragma once
 
@@ skipping 267 matching lines @@
 // The URL for the "Learn more" page for register protocol handler infobars.
 extern const char kLearnMoreRegisterProtocolHandlerURL[];
 
 // The URL for the "Learn more" page for sync setup on the personal stuff page.
 extern const char kSyncLearnMoreURL[];
 
 // "Debug" pages which are dangerous and not for general consumption.
 extern const char* const kChromeDebugURLs[];
 extern int kNumberOfChromeDebugURLs;
 
+// Canonical schemes you can use as input to GURL.SchemeIs().
+extern const char kExtensionScheme[];
+
 // Call near the beginning of startup to register Chrome's internal URLs that
 // should be parsed as "standard" with the googleurl library.
 void RegisterChromeSchemes();
 
 #if defined(OS_CHROMEOS)
 // "Learn more" URL for the Cloud Print section under Options.
 extern const char kCloudPrintLearnMoreURL[];
 #endif
 
 }  // namespace chrome
 
 #endif  // CHROME_COMMON_URL_CONSTANTS_H_