Cleanup taskbar touchableInsets

- Remove obsolete visibleInsets hack and isDraggingItem() check
- Have TaskbarController determine whether taskbar is touchable,
  rather than TaskbarContainerView.
- Disallow touches during transition to home (can potentially
  improve this later)

Test: Swupe home, tap taskbar folder during transition, ensure
don't end up in broken state with the uninteractable folder open
Bug: 182512211

Change-Id: Id625ce8b9b876a8a1b450b7d6fb771540e23bc08

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

@@ -42,6 +42,7 @@ import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.LauncherState;
 import com.android.launcher3.QuickstepTransitionManager;
 import com.android.launcher3.R;
+import com.android.launcher3.anim.AlphaUpdateListener;
 import com.android.launcher3.anim.PendingAnimation;
 import com.android.launcher3.folder.Folder;
 import com.android.launcher3.folder.FolderIcon;
@@ -141,6 +142,13 @@ public class TaskbarController {
                     setTaskbarWindowFullscreen(false);
                 }
             }
+
+            @Override
+            public boolean isTaskbarTouchable() {
+                return mTaskbarContainerView.getAlpha() > AlphaUpdateListener.ALPHA_CUTOFF_THRESHOLD
+                        && mTaskbarViewInApp.getVisibility() == View.VISIBLE
+                        && !mIsAnimatingToLauncher;
+            }
         };
     }
 
@@ -549,6 +557,7 @@ public class TaskbarController {
      */
     protected interface TaskbarContainerViewCallbacks {
         void onViewRemoved();
+        boolean isTaskbarTouchable();
     }
 
     /**