Bring screen lock setting back to screen pinning

The material design of the request has removed this option from
the dialog, and now needs to be in settings.  When screen
pinning is off it shows a description of how to use the feature,
however when on it shows a switch to control whether it locks
the device on exit.  This setting defaults to on if there is a
lock pin/pattern.

Bug: 16957435
Change-Id: I59e0d64964cee4302e6ecff59e622cfe11422807
diff --git a/res/values/strings.xml b/res/values/strings.xml
index f8721c3..3091727 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -5903,6 +5903,14 @@
     <string name="screen_pinning_title">Screen pinning</string>
     <!-- [CHAR LIMIT=300] Screen pinning description -->
     <string name="screen_pinning_description">When turned on, you can use screen pinning to keep the current screen in view until you unpin.\n\nTo use screen pinning:\n\n1. Make sure screen pinning is turned on.\n\n2. Open the screen you want to pin.\n\n3. Touch Overview.\n\n4. Touch the pin icon.</string>
+    <!-- [CHAR LIMIT=60] Unlock setting for screen pinning -->
+    <string name="screen_pinning_unlock_pattern">Ask for unlock pattern before unpinning</string>
+    <!-- [CHAR LIMIT=60] Unlock setting for screen pinning -->
+    <string name="screen_pinning_unlock_pin">Ask for PIN before unpinning</string>
+    <!-- [CHAR LIMIT=60] Unlock setting for screen pinning -->
+    <string name="screen_pinning_unlock_password">Ask for password before unpinning</string>
+    <!-- [CHAR LIMIT=60] Unlock setting for screen pinning -->
+    <string name="screen_pinning_unlock_none">Lock device when unpinning</string>
 
     <!-- Title for a work profile. [CHAR LIMIT=25] -->
     <string name="managed_user_title">Work profile</string>