Don't schedule periodic update checks for non-official builds.

utils.cc

Index: utils.cc
diff --git a/utils.cc b/utils.cc
index 4c5a195cf4982246ce06d1c68f1ced5a12856b5a..d691739bb3100d77cb4da3ad6fe4a78327569f70 100644
--- a/utils.cc
+++ b/utils.cc
@@ -16,6 +16,7 @@
 #include <algorithm>
 #include "chromeos/obsolete_logging.h"
 #include "update_engine/file_writer.h"
+#include "update_engine/omaha_request_params.h"
 #include "update_engine/subprocess.h"
 
 using std::min;
@@ -26,6 +27,15 @@ namespace chromeos_update_engine {
 
 namespace utils {
 
+bool IsOfficialBuild() {
+  OmahaRequestDeviceParams params;
+  if (!params.Init("", "")) {
+    return true;
+  }
+  return params.app_track != "buildbot-build" &&
+      params.app_track != "developer-build";
+}
+
 bool WriteFile(const char* path, const char* data, int data_len) {
   DirectFileWriter writer;
   TEST_AND_RETURN_FALSE_ERRNO(0 == writer.Open(path,