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/libcurl_http_fetcher.h b/libcurl_http_fetcher.h
index a59a56e..a3b7919 100644
--- a/libcurl_http_fetcher.h
+++ b/libcurl_http_fetcher.h
@@ -28,8 +28,7 @@
 class LibcurlHttpFetcher : public HttpFetcher {
  public:
   LibcurlHttpFetcher(ProxyResolver* proxy_resolver,
-                     SystemState* system_state,
-                     bool is_test_mode)
+                     SystemState* system_state)
       : HttpFetcher(proxy_resolver, system_state),
         curl_multi_handle_(NULL),
         curl_handle_(NULL),
@@ -50,7 +49,6 @@
         sent_byte_(false),
         terminate_requested_(false),
         check_certificate_(CertificateChecker::kNone),
-        is_test_mode_(is_test_mode),
         low_speed_limit_bps_(kDownloadLowSpeedLimitBps),
         low_speed_time_seconds_(kDownloadLowSpeedTimeSeconds),
         connect_timeout_seconds_(kDownloadConnectTimeoutSeconds) {
@@ -276,9 +274,6 @@
   // this should be kNone.
   CertificateChecker::ServerToCheck check_certificate_;
 
-  // If true, utilizes a relaxed test mode fetch logic. False by default.
-  bool is_test_mode_;
-
   int low_speed_limit_bps_;
   int low_speed_time_seconds_;
   int connect_timeout_seconds_;