AU: Timestamp logs at startup.

This will allow logs to be rotated by init/chromeos-cleanup-logs (separate CL).

BUG=5527
TEST=tested on device, chrome://system

Change-Id: I844ebd198510a8f600afa99f840624b2e65d1584

Review URL: http://codereview.chromium.org/4771007
diff --git a/utils.h b/utils.h
index 208abe8..34b862e 100644
--- a/utils.h
+++ b/utils.h
@@ -60,6 +60,9 @@
 // or an error occurs.
 bool FileExists(const char* path);
 
+// Returns true if |path| exists and is a symbolic link.
+bool IsSymlink(const char* path);
+
 // The last 6 chars of path must be XXXXXX. They will be randomly changed
 // and a non-existent path will be returned. Intentionally makes a copy
 // of the string passed in.