Revert "update_engine: Support milestones to EOL from Omaha"

This reverts commit 893cae4b0e5141bcaf9f56b1775e681c8f523630.

Reason for revert: use of EOL date and EOL notification date instead milestones to EOL.

Original change's description:
> update_engine: Support milestones to EOL from Omaha
>
> Initiative to show EOL message on Chrome OS devices require that
> update_engine parses the fields within Omaha response that pertain to the
> new milestones to EOL field. The Omaha response will include a new
> field called "milestones_to_eol" which will be an integer value
> string.
>
> The job of update_engine when it comes to milestones to EOL from Omaha
> is to merely forward. No checks and no modifications of fields are
> done within update_engine besides being able to convert the milestones
> to EOL from a string to integer.
>
> BUG=chromium:994999
> TEST=FEATURES="test" emerge-$BOARD update_engine update_engine-client
> TEST=cros deploy $IP update_engine update_engine-client
> TEST=test_that -b $BOARD $IP autoupdate_EOL # from Cq-Depend
> TEST=test_that -b $BOARD $IP autoupdate_EOL.milestones # from Cq-Depend
>
> Cq-Depend:chromium:1761371
> Change-Id: I268e4c8e641b17d6a727a50f53285cc97c76eb22
> Reviewed-on: https://chromium-review.googlesource.com/1759285
> Tested-by: Jae Hoon Kim <kimjae@chromium.org>
> Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
> Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
> Reviewed-by: Nicolas Norvez <norvez@chromium.org>
> Reviewed-by: Amin Hassani <ahassani@chromium.org>

TBR=maybelle@chromium.org,norvez@chromium.org,ahassani@chromium.org,abutzier@chromium.org,chromiumos-cl-exonerator@appspot.gserviceaccount.com,kimjae@chromium.org

BUG=chromium:994999
TEST=none
Cq-Depend:chromium:1782971
Change-Id: I42e75e22948b3653500d355027dc3312015c9ebf
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/1782970
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Queue: Jae Hoon Kim <kimjae@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/common_service.cc b/common_service.cc
index 466007f..0d5ee6d 100644
--- a/common_service.cc
+++ b/common_service.cc
@@ -413,31 +413,18 @@
 }
 
 bool UpdateEngineService::GetEolStatus(ErrorPtr* error,
-                                       int32_t* out_eol_status,
-                                       int32_t* out_milestones_to_eol) {
+                                       int32_t* out_eol_status) {
   PrefsInterface* prefs = system_state_->prefs();
 
-  // Set EOL.
   string str_eol_status;
   if (prefs->Exists(kPrefsOmahaEolStatus) &&
       !prefs->GetString(kPrefsOmahaEolStatus, &str_eol_status)) {
     LogAndSetError(error, FROM_HERE, "Error getting the end-of-life status.");
     return false;
   }
-  // |StringToEolStatus()| will return |kSupported| for invalid values.
+
+  // StringToEolStatus will return kSupported for invalid values.
   *out_eol_status = static_cast<int32_t>(StringToEolStatus(str_eol_status));
-
-  // Set milestones to EOL.
-  string str_milestones_to_eol;
-  if (prefs->Exists(kPrefsOmahaMilestonesToEol) &&
-      !prefs->GetString(kPrefsOmahaMilestonesToEol, &str_milestones_to_eol)) {
-    LogAndSetError(error, FROM_HERE, "Error getting the milestones to EOL.");
-    return false;
-  }
-  // |StringToMilestonesToEol()| will return |kMilestonesToEolNone| for invalid
-  // values.
-  *out_milestones_to_eol = StringToMilestonesToEol(str_milestones_to_eol);
-
   return true;
 }