[gnome-boxes] util: Add is_mime_type()

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit a9e6af5fa88c3748bbf748f68450eea95dd2b3b8
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Wed Jun 5 04:02:33 2013 +0300

    util: Add is_mime_type()
    
    Add utility function to determine if given file is on given mimetype.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=690757

 src/util-app.vala |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/src/util-app.vala b/src/util-app.vala
index ae184be..d15c0af 100644
--- a/src/util-app.vala
+++ b/src/util-app.vala
@@ -530,6 +530,13 @@ namespace Boxes {
         return tokens[1];
     }
 
+    public bool is_mime_type (string filename, string mime_type) {
+        var file_type = ContentType.guess (filename, null, null);
+        var supertype = ContentType.from_mime_type (mime_type);
+
+        return ContentType.is_a (file_type, supertype);
+    }
+
     namespace UUID {
         [CCode (cname = "uuid_generate", cheader_filename = "uuid/uuid.h")]
         internal extern static void generate ([CCode (array_length = false)] uchar[] uuid);