Remove dead code SavePasswordsPreferences#onPreferenceChange

SavePasswordsPreferences never registers itself as an
OnPreferenceChangeListener so its onPreferenceChange method never gets
called. This CL removes that dead code.

Note that OnPreferenceChangeListener is still used in-line, so the
import is not removed.

Bug: 788701
Change-Id: I87ae4f6be3e2dc4322fad56551338b0a8355e062
Reviewed-on: https://chromium-review.googlesource.com/808265Reviewed-by: Finnur Thorarinsson <finnur@chromium.org>
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521691}

chrome/android/java/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferences.java

@@ -38,9 +38,7 @@ import org.chromium.ui.text.SpanApplier;
  * saving, to view saved passwords (just the username and URL), and to delete saved passwords.
  */
 public class SavePasswordsPreferences extends PreferenceFragment
-        implements OnPreferenceChangeListener, PasswordListObserver,
-        Preference.OnPreferenceClickListener {
-
+        implements PasswordListObserver, Preference.OnPreferenceClickListener {
     // Keys for name/password dictionaries.
     public static final String PASSWORD_LIST_URL = "url";
     public static final String PASSWORD_LIST_NAME = "name";
@@ -113,12 +111,6 @@ public class SavePasswordsPreferences extends PreferenceFragment
         getPreferenceScreen().addPreference(mEmptyView);
     }
 
-    @Override
-    public boolean onPreferenceChange(Preference preference, Object newValue) {
-        rebuildPasswordLists();
-        return true;
-    }
-
     @Override
     public void onDetach() {
         super.onDetach();