Coalesce more hardcoded schemes to using predefined constants.

chrome/common/url_constants.h

Index: chrome/common/url_constants.h
===================================================================
--- chrome/common/url_constants.h	(revision 10348)
+++ chrome/common/url_constants.h	(working copy)
@@ -11,11 +11,25 @@
 
 // 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_