Don't set a task description for work lock overlay

Just use the one in the previous activity on the task stack, it's less
code and also has the benefit that if anything new happens in that
activity, all of the observers will be notified about the new
description straight away.

Bug: 29244275
Test: adb shell service call trust 6 i32 10 i32 1 && adb shell am start -a com.android.systemui.recents.TOGGLE_RECENTS
Change-Id: I56d3b627ccda82cd2a2e520de0e170e4fa4acc77

packages/SystemUI/src/com/android/systemui/keyguard/WorkLockActivity.java

@@ -91,10 +91,6 @@ public class WorkLockActivity extends Activity {
         // Draw captions overlaid on the content view, so the whole window is one solid color.
         setOverlayWithDecorCaptionEnabled(true);
 
-        // Match task description to the task stack we are replacing so it's still recognizably the
-        // original task stack with the same icon and title text.
-        setTaskDescription(new TaskDescription(null, null, color));
-
         // Blank out the activity. When it is on-screen it will look like a Recents thumbnail with
         // redaction switched on.
         final View blankView = new View(this);
@@ -127,6 +123,11 @@ public class WorkLockActivity extends Activity {
         return;
     }
 
+    @Override
+    public void setTaskDescription(TaskDescription taskDescription) {
+        // Use the previous activity's task description.
+    }
+
     private final BroadcastReceiver mLockEventReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {