Hide taskbar on lockscreen

Add new animated float to disable taskbar
background value when keyguard is visible.

Fixes: 191857724
Test: Tested w/ and w/o bouncer for gesture + 3 button
Tested w/ IME pw on lock screen.

Change-Id: I2e1696fd25f4c170bfb2bc0694ccd644e453b1fe

quickstep/src/com/android/launcher3/taskbar/TaskbarDragLayerController.java

@@ -39,6 +39,7 @@ public class TaskbarDragLayerController {
     // Alpha properties for taskbar background.
     private final AnimatedFloat mBgTaskbar = new AnimatedFloat(this::updateBackgroundAlpha);
     private final AnimatedFloat mBgNavbar = new AnimatedFloat(this::updateBackgroundAlpha);
+    private final AnimatedFloat mKeyguardBgTaskbar = new AnimatedFloat(this::updateBackgroundAlpha);
     // Translation property for taskbar background.
     private final AnimatedFloat mBgOffset = new AnimatedFloat(this::updateBackgroundOffset);
 
@@ -56,6 +57,7 @@ public class TaskbarDragLayerController {
     public void init(TaskbarControllers controllers) {
         mControllers = controllers;
         mTaskbarDragLayer.init(new TaskbarDragLayerCallbacks());
+        mKeyguardBgTaskbar.value = 1;
     }
 
     public void onDestroy() {
@@ -80,12 +82,18 @@ public class TaskbarDragLayerController {
         return mBgNavbar;
     }
 
+    public AnimatedFloat getKeyguardBgTaskbar() {
+        return mKeyguardBgTaskbar;
+    }
+
     public AnimatedFloat getTaskbarBackgroundOffset() {
         return mBgOffset;
     }
 
     private void updateBackgroundAlpha() {
-        mTaskbarDragLayer.setTaskbarBackgroundAlpha(Math.max(mBgNavbar.value, mBgTaskbar.value));
+        mTaskbarDragLayer.setTaskbarBackgroundAlpha(
+                Math.max(mBgNavbar.value, mBgTaskbar.value * mKeyguardBgTaskbar.value)
+        );
     }
 
     private void updateBackgroundOffset() {