[Android] Hide SyncPromo after user gives sync consent

After going through the sync consent flow from SyncPromoPreference, this
preference should be hidden. Keeping the SyncPromoPreference when
SigninPromoController was not null was preventing that from happening.

Bug: 1126074
Change-Id: Ibad0838ec2594b1c6825561df4d6392359fe7c9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2400418Reviewed-by: Tanmoy Mollik <triploblastic@chromium.org>
Reviewed-by: Alice Wang <aliceywang@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Tanmoy Mollik <triploblastic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807823}

chrome/android/java/src/org/chromium/chrome/browser/sync/settings/SyncPromoPreference.java

@@ -126,12 +126,6 @@ public class SyncPromoPreference extends Preference
             return;
         }
 
-        if (mSigninPromoController != null) {
-            // Don't change the promo type if the new promo is already being shown.
-            setupPersonalizedSyncPromo();
-            return;
-        }
-
         setupPromoHidden();
     }