convert to print_function

BUG=chromium:414895
TEST=`./cbuildbot/run_tests` passes
TEST=`cros lint` passes (it complains if print is used incorrectly)
TEST=`cbuildbot chromiumos-sdk` passes
TEST=`cbuildbot lumpy-release` passes

Change-Id: I67e7e1290b03a16525e0c2b1afa74ebbd8d3508f
Reviewed-on: https://chromium-review.googlesource.com/218572
Reviewed-by: David James <davidjames@chromium.org>
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cros_sdk.py b/scripts/cros_sdk.py
index 84a4711..822cef0 100644
--- a/scripts/cros_sdk.py
+++ b/scripts/cros_sdk.py
@@ -4,6 +4,8 @@
 
 """This script fetches and prepares an SDK chroot."""
 
+from __future__ import print_function
+
 import errno
 import glob
 import os
@@ -93,7 +95,7 @@
         return parsed.path
       continue
     content_length = 0
-    print 'Attempting download: %s' % url
+    print('Attempting download: %s' % url)
     result = retry_util.RunCurl(
           ['-I', url], redirect_stdout=True, redirect_stderr=True,
           print_cmd=False)
@@ -133,7 +135,7 @@
     if filename == tarball_name or filename.startswith(ignored_prefix):
       continue
 
-    print 'Cleaning up old tarball: %s' % (filename,)
+    print('Cleaning up old tarball: %s' % (filename,))
     osutils.SafeUnlink(os.path.join(storage_dir, filename))
 
   return tarball_dest