Add google_update::GetUntrustedDataValueFromTag()

chrome/installer/util/google_update_util.h

Index: chrome/installer/util/google_update_util.h
diff --git a/chrome/installer/util/google_update_util.h b/chrome/installer/util/google_update_util.h
index 30d77e95b6519f1af197fd9e86225440473ce2fd..8ef2b9a7539c9e09f5f7c00060a1a6efb1b1c916 100644
--- a/chrome/installer/util/google_update_util.h
+++ b/chrome/installer/util/google_update_util.h
@@ -27,6 +27,13 @@ bool UninstallGoogleUpdate(bool system_install);
 // contains non-printable characters.
 std::string GetUntrustedDataValue(const std::string& key);
 
+// Returns the value corresponding to |key| in untrusted data passed from
+// |tag|.  |tag| should be a printable list of key-value pairs, e.g.
+// "key1=value1&key2=value2".  Returns an empty string if |key| is absent or if
+// its value contains non-printable characters.
+std::string GetUntrustedDataValueFromTag(const std::string& tag,
+                                         const std::string& key);
+
 }  // namespace google_update
 
 #endif  // CHROME_INSTALLER_UTIL_GOOGLE_UPDATE_UTIL_H_