Update update engine to compile and use libchrome-180609.

Made the following fixes:
- base/eintr_wrapper.h -> base/posix/eintr_wrapper.h
- base/string_tokenizer.h -> base/strings/string_tokenizer.h
- Switched JSONReader->JsonToValue to use JSONReader->ReadToValue.

BUG=chromium-os:39847
TEST=unittests + run through image_to_live

Change-Id: Iffa0a3af4a065fac40460d8c1c2ed5c9b6e9ed07
Reviewed-on: https://gerrit.chromium.org/gerrit/44098
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Chris Sosa <sosa@chromium.org>
diff --git a/utils.h b/utils.h
index 6c17853..569556c 100644
--- a/utils.h
+++ b/utils.h
@@ -12,7 +12,7 @@
 #include <unistd.h>
 #include <vector>
 
-#include <base/eintr_wrapper.h>
+#include <base/posix/eintr_wrapper.h>
 #include <base/time.h>
 #include <ext2fs/ext2fs.h>
 #include <glib.h>