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/subprocess_unittest.cc b/subprocess_unittest.cc
index 3933f25..d9b212b 100644
--- a/subprocess_unittest.cc
+++ b/subprocess_unittest.cc
@@ -19,11 +19,12 @@
 
 #include <base/bind.h>
 #include <base/location.h>
+#include <base/message_loop/message_loop.h>
 #include <base/strings/string_util.h>
 #include <base/strings/stringprintf.h>
 #include <base/time/time.h>
 #include <chromeos/bind_lambda.h>
-#include <chromeos/message_loops/glib_message_loop.h>
+#include <chromeos/message_loops/base_message_loop.h>
 #include <chromeos/message_loops/message_loop.h>
 #include <chromeos/message_loops/message_loop_utils.h>
 #include <chromeos/strings/string_utils.h>
@@ -47,9 +48,8 @@
     subprocess_.Init(&async_signal_handler_);
   }
 
-  // TODO(deymo): Replace this with a FakeMessageLoop. Subprocess uses glib to
-  // asynchronously spawn a process, so we need to run a GlibMessageLoop here.
-  chromeos::GlibMessageLoop loop_;
+  base::MessageLoopForIO base_loop_;
+  chromeos::BaseMessageLoop loop_{&base_loop_};
   chromeos::AsynchronousSignalHandler async_signal_handler_;
   Subprocess subprocess_;
 };