update_engine: Remove all references to glib.

The message loop in production code switched from
chromeos::GlibMessageLoop to chromeos::BaseMessageLoop used in
chromeos::Dameon. This patch moves all the unittests also to use
chromeos::BaseMessageLoop or chromeos::FakeMessageLoop when I/O is not
required.

This patch removes all (now unused) references to glib.

BUG=chromium:499886
TEST=`grep glib[^c] . -R` return no results. Also, unittests work.

Change-Id: Iddfb17def501829d932ed1f70faad3e00268898e
Reviewed-on: https://chromium-review.googlesource.com/292157
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Trybot-Ready: Alex Deymo <deymo@chromium.org>
diff --git a/libcurl_http_fetcher.h b/libcurl_http_fetcher.h
index 4f68a9a..1b8891d 100644
--- a/libcurl_http_fetcher.h
+++ b/libcurl_http_fetcher.h
@@ -129,7 +129,7 @@
 
   // Calls into curl_multi_perform to let libcurl do its work. Returns after
   // curl_multi_perform is finished, which may actually be after more than
-  // one call to curl_multi_perform. This method will set up the glib run
+  // one call to curl_multi_perform. This method will set up the message
   // loop with sources for future work that libcurl will do.
   // This method will not block.
   // Returns true if we should resume immediately after this call.