Fix 2209086: Fix visual glitches in lockscreen.

Call new setHoldAfterTrigger() method to enable feature added in https://android-git.corp.google.com/g/#change,33380.
diff --git a/phone/com/android/internal/policy/impl/LockScreen.java b/phone/com/android/internal/policy/impl/LockScreen.java
index a58cfb7..67fe0b3 100644
--- a/phone/com/android/internal/policy/impl/LockScreen.java
+++ b/phone/com/android/internal/policy/impl/LockScreen.java
@@ -188,6 +188,7 @@
         mEmergencyCallButton.setText(R.string.lockscreen_emergency_call);
         mScreenLocked = (TextView) findViewById(R.id.screenLocked);
         mSelector = (SlidingTab) findViewById(R.id.tab_selector);
+        mSelector.setHoldAfterTrigger(true, false);
         mSelector.setLeftHintText(R.string.lockscreen_unlock_label);
         mEmergencyCallButton.setOnClickListener(new View.OnClickListener() {
             public void onClick(View v) {