Improve Taskbar touchableRegion debuggability

- Add DebugTouchableRegion which includes the last region that we
  set as well as the reason (code path) for it, which we dump.
- If persist.debug.draw_taskbar_debug_ui is enabled, we will also
  outline the touchable region on the screen.

Flag: None
Test: testThreeButtonsTaskbarBoundsAfterConfigChangeDuringIme
Bug: 315393203

Change-Id: I70b37e8b8804c4a48ffe3956d2a24aa5eab452fd

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

@@ -19,8 +19,10 @@ import static com.android.launcher3.taskbar.TaskbarPinningController.PINNING_PER
 import static com.android.launcher3.taskbar.TaskbarPinningController.PINNING_TRANSIENT;
 
 import android.content.res.Resources;
+import android.graphics.Canvas;
 import android.graphics.Point;
 import android.graphics.Rect;
+import android.os.SystemProperties;
 import android.view.ViewTreeObserver;
 
 import com.android.launcher3.DeviceProfile;
@@ -39,6 +41,9 @@ import java.io.PrintWriter;
 public class TaskbarDragLayerController implements TaskbarControllers.LoggableTaskbarController,
         TaskbarControllers.BackgroundRendererController {
 
+    private static final boolean DEBUG = SystemProperties.getBoolean(
+            "persist.debug.draw_taskbar_debug_ui", false);
+
     private final TaskbarActivityContext mActivity;
     private final TaskbarDragLayer mTaskbarDragLayer;
     private final int mFolderMargin;
@@ -299,5 +304,15 @@ public class TaskbarDragLayerController implements TaskbarControllers.LoggableTa
                     mTaskbarStashViaTouchController,
             };
         }
+
+        /**
+         * Draws debug UI on top of everything in TaskbarDragLayer.
+         */
+        public void drawDebugUi(Canvas canvas) {
+            if (!DEBUG) {
+                return;
+            }
+            mControllers.taskbarInsetsController.drawDebugTouchableRegionBounds(canvas);
+        }
     }
 }