AU: Switch GLib's timeout sources from milliseconds to seconds.

There's no need for the extra resolution and seconds is preferred.

BUG=5577
TEST=unit tests, gmerged on device and saw checks at 2 and 30 minutes.

Change-Id: I6d64774d5a0e8961fbb9868edc42e62eb794ba11

Review URL: http://codereview.chromium.org/3183004
diff --git a/main.cc b/main.cc
index c196ed5..3ae1e4b 100644
--- a/main.cc
+++ b/main.cc
@@ -60,8 +60,8 @@
 
   // Kick off periodic updating. First, update after 2 minutes. Also, update
   // every 30 minutes.
-  g_timeout_add(2 * 60 * 1000, &UpdateOnce, update_attempter);
-  g_timeout_add(30 * 60 * 1000, &UpdatePeriodically, update_attempter);
+  g_timeout_add_seconds(2 * 60, &UpdateOnce, update_attempter);
+  g_timeout_add_seconds(30 * 60, &UpdatePeriodically, update_attempter);
 }
 
 void SetupDbusService(UpdateEngineService* service) {