Change taskbar corner roundness when entering overview

- Roundness will be 0 in Launcher, and 1 in an app

Bug: 250645563
Test: With and without taskbar in overview, switch between home/overview/app and observe the round corners above taskbar
Test: Ensure corner above taskbar is correct in overview and in app when chat bubble is active
Change-Id: I1f4911626c8e79fce8d81a76a9bd0d0670d111da

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

@@ -32,7 +32,8 @@ import java.io.PrintWriter;
 /**
  * Handles properties/data collection, then passes the results to TaskbarDragLayer to render.
  */
-public class TaskbarDragLayerController implements TaskbarControllers.LoggableTaskbarController {
+public class TaskbarDragLayerController implements TaskbarControllers.LoggableTaskbarController,
+        TaskbarControllers.BackgroundRendererController {
 
     private final TaskbarActivityContext mActivity;
     private final TaskbarDragLayer mTaskbarDragLayer;
@@ -138,6 +139,11 @@ public class TaskbarDragLayerController implements TaskbarControllers.LoggableTa
         updateNavBarDarkIntensityMultiplier();
     }
 
+    @Override
+    public void setCornerRoundness(float cornerRoundness) {
+        mTaskbarDragLayer.setCornerRoundness(cornerRoundness);
+    }
+
     private void updateNavBarDarkIntensityMultiplier() {
         // Zero out the app-requested dark intensity when we're drawing our own background.
         float effectiveBgAlpha = mLastSetBackgroundAlpha * (1 - mBgOffset.value);