[Signin] Clean up unused method in VariationsSession.

chrome/android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java

Index: chrome/android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java b/chrome/android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java
index 4ac571edd423f0f1267485ab0cd49684249180e7..bbb2bc642c82ad280ae871fdec80a41f2fb70750 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java
@@ -41,12 +41,7 @@ public class VariationsSession {
      * should use for variation seed requests.
      */
     protected void getRestrictMode(Context context, Callback<String> callback) {
-        callback.onResult(getRestrictMode(context));
-    }
-
-    // TODO(maxbogue): Remove once downstream is updated to be async.
-    protected String getRestrictMode(Context context) {
-        return "";
+        callback.onResult("");
     }
 
     private native void nativeStartVariationsSession(String restrictMode);