update_engine: Remove GPIO support.

We have not used GPIO since Jan 2013. This CL removes the GPIO handling code.
As a side effect, it also removes dependency on libudev.

BUG=chromium:221725
CQ-DEPEND=CL:199683
TEST=unittest
TEST=AU end2end test on real device from older version to a version that
has CL applied, then from that to another newer version (need not have
this CL applied).

Change-Id: I4352488ec360b44a44b137c40a3ae4ec35c6fe9d
Reviewed-on: https://chromium-review.googlesource.com/199626
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>
diff --git a/update_attempter_mock.h b/update_attempter_mock.h
index d2bc447..3bde347 100644
--- a/update_attempter_mock.h
+++ b/update_attempter_mock.h
@@ -15,11 +15,10 @@
  public:
   using UpdateAttempter::UpdateAttempter;
 
-  MOCK_METHOD5(Update, void(const std::string& app_version,
+  MOCK_METHOD4(Update, void(const std::string& app_version,
                             const std::string& omaha_url,
                             bool obey_proxies,
-                            bool interactive,
-                            bool is_test));
+                            bool interactive));
 
   MOCK_METHOD5(GetStatus, bool(int64_t* last_checked_time,
                                double* progress,