shill: fix printf format in manager_unittest

fix printf format in manager_unittest

BUG=none
TEST=FEATURES="test noclean" emerge-x86-alex shill

Change-Id: Iffce6a152f579f995302f1754297bfe10a624ec6
Reviewed-on: https://gerrit.chromium.org/gerrit/14946
Tested-by: Jason Glasgow <jglasgow@chromium.org>
Reviewed-by: Zdenek Behan <zbehan@chromium.org>
Commit-Ready: Jason Glasgow <jglasgow@chromium.org>
diff --git a/manager_unittest.cc b/manager_unittest.cc
index 534f7a0..004ee62 100644
--- a/manager_unittest.cc
+++ b/manager_unittest.cc
@@ -1114,7 +1114,7 @@
   for (size_t i = 0; i < 10; i++) {
     scoped_refptr<MockProfile> profile(
       new StrictMock<MockProfile>(control_interface(), manager(), ""));
-    profile_paths.push_back(base::StringPrintf("/profile/%d", i));
+    profile_paths.push_back(base::StringPrintf("/profile/%zd", i));
     EXPECT_CALL(*profile.get(), GetRpcIdentifier())
         .WillOnce(Return(profile_paths.back()));
     AdoptProfile(manager(), profile);