gdata: Support opening zip file on Google Docs.

chromeos/dbus/cros_disks_client.h

Index: chromeos/dbus/cros_disks_client.h
diff --git a/chromeos/dbus/cros_disks_client.h b/chromeos/dbus/cros_disks_client.h
index 88e6aee998188fbfe60cfdeab6c60f6420c7f582..a4ea8c40ba0e0d38644ebcfd52830fee09906676 100644
--- a/chromeos/dbus/cros_disks_client.h
+++ b/chromeos/dbus/cros_disks_client.h
@@ -178,7 +178,11 @@ class CHROMEOS_EXPORT CrosDisksClient {
 
   // Calls Mount method.  |callback| is called after the method call succeeds,
   // otherwise, |error_callback| is called.
+  // When mounting an archive, the |source_format| argument passes the file
+  // extension (with the leading dot, for example ".zip"). If |source_format| is
+  // empty then the source format is auto-detected.
   virtual void Mount(const std::string& source_path,
+                     const std::string& source_format,
                      MountType type,
                      const MountCallback& callback,
                      const ErrorCallback& error_callback) = 0;