Coalesce more hardcoded schemes to using predefined constants.

chrome/common/url_constants.h

 // Copyright (c) 2006-2008 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_
 
 namespace chrome {
 
 // Canonical schemes you can use as input to GURL.SchemeIs().
 extern const char kAboutScheme[];
-extern const char kChromeUIScheme[];
+extern const char kChromeInternalScheme[];  // Used for new tab page.
+extern const char kChromeUIScheme[];  // The scheme used for DOMUIContentses.
 extern const char kDataScheme[];
+extern const char kExtensionScheme[];
+extern const char kFileScheme[];
+extern const char kFtpScheme[];
+extern const char kHttpScheme[];
+extern const char kHttpsScheme[];
 extern const char kJavaScriptScheme[];
+extern const char kMailToScheme[];
+extern const char kUserScriptScheme[];
 extern const char kViewSourceScheme[];
 
+// Used to separate a standard scheme and the hostname: "://".
+extern const char kStandardSchemeSeparator[];
+
+// About URLs (including schmes).
+extern const char kAboutBlankURL[];
+
 }  // namespace chrome
 
 #endif  // CHROME_COMMON_URL_CONSTANTS_H_