Fixed unnecessary layer creations in the pin unlock method

This was especially noticible when double tapping a notification
because of the staggered appearing.

Bug: 17287256
Change-Id: I8f39892fa122bb8b7b6f2a7b1e7be8a9570e661e
diff --git a/packages/Keyguard/src/com/android/keyguard/NumPadKey.java b/packages/Keyguard/src/com/android/keyguard/NumPadKey.java
index 2d20b02..d539856 100644
--- a/packages/Keyguard/src/com/android/keyguard/NumPadKey.java
+++ b/packages/Keyguard/src/com/android/keyguard/NumPadKey.java
@@ -152,6 +152,11 @@
         mKlondikeText.layout(left, top, left + mKlondikeText.getMeasuredWidth(), bottom);
     }
 
+    @Override
+    public boolean hasOverlappingRendering() {
+        return false;
+    }
+
     // Cause a VIRTUAL_KEY vibration
     public void doHapticKeyClick() {
         if (mEnableHaptics) {
diff --git a/packages/Keyguard/src/com/android/keyguard/PasswordTextView.java b/packages/Keyguard/src/com/android/keyguard/PasswordTextView.java
index f3ba3a7..6497f46 100644
--- a/packages/Keyguard/src/com/android/keyguard/PasswordTextView.java
+++ b/packages/Keyguard/src/com/android/keyguard/PasswordTextView.java
@@ -145,6 +145,11 @@
         }
     }
 
+    @Override
+    public boolean hasOverlappingRendering() {
+        return false;
+    }
+
     private Rect getCharBounds() {
         float textHeight = mTextHeightRaw * getResources().getDisplayMetrics().scaledDensity;
         mDrawPaint.setTextSize(textHeight);