Move some content url constants to /url.

url/url_constants.cc

Index: url/url_constants.cc
diff --git a/url/url_constants.cc b/url/url_constants.cc
index 7df30dac98cfb2eb6afcbf3618bb1c877df30f66..2949d44aaf2a12430e5b050e3baa94ce9e88f6bd 100644
--- a/url/url_constants.cc
+++ b/url/url_constants.cc
@@ -6,7 +6,14 @@
 
 namespace url {
 
+const char kBlobScheme[] = "blob";
+const char kDataScheme[] = "data";
+const char kFileScheme[] = "file";
+const char kFileSystemScheme[] = "filesystem";
+const char kFtpScheme[] = "ftp";
 const char kHttpScheme[] = "http";
 const char kHttpsScheme[] = "https";
+const char kJavaScriptScheme[] = "javascript";
+const char kMailToScheme[] = "mailto";
 
 }  // namespace url