Add summary for 0 fingerprint settings preference

This allows the fingerprint summary to be shown when there
are no fingerprints.

Fixes bug 24172006

Change-Id: I9dd266013ac74da74f1dd397cbe0e50acf5d1262

res/values/strings.xml

@@ -707,6 +707,8 @@
         <item quantity="one"><xliff:g id="count">%1$d</xliff:g> fingerprint set up</item>
         <item quantity="other"><xliff:g id="count">%1$d</xliff:g> fingerprints set up</item>
     </plurals>
+    <!-- message shown in summary field when no fingerprints are registered -->
+    <string name="security_settings_fingerprint_preference_summary_none"></string>
     <!-- Introduction title shown in fingerprint enrollment dialog [CHAR LIMIT=29] -->
     <string name="security_settings_fingerprint_enroll_onboard_title">Fingerprint setup</string>
     <!-- Introduction message shown in fingerprint enrollment dialog when the user needs to choose an

src/com/android/settings/SecuritySettings.java

@@ -361,6 +361,8 @@ public class SecuritySettings extends SettingsPreferenceFragment
                     fingerprintCount, fingerprintCount));
             clazz = FingerprintSettings.class.getName();
         } else {
+            fingerprintPreference.setSummary(
+                    R.string.security_settings_fingerprint_preference_summary_none);
             clazz = FingerprintEnrollIntroduction.class.getName();
         }
         intent.setClassName("com.android.settings", clazz);