Add flags to stash taskbar for app pinning and empty hotseat

Test: pin an app from overview, watch taskbar stash automatically until unpinning
Test: turn off suggestions for hotseat, remove all items and watch taskbar stash automatically when opening an app
Fixes: 190192993
Fixes: 193937948
Change-Id: Ia7260c60a820af1a48c9e4a400a52753baf34d41

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

@@ -45,6 +45,9 @@ public class TaskbarModelCallbacks implements
     private final TaskbarActivityContext mContext;
     private final TaskbarView mContainer;
 
+    // Initialized in init.
+    private TaskbarControllers mControllers;
+
     private boolean mBindInProgress = false;
 
     public TaskbarModelCallbacks(
@@ -53,6 +56,10 @@ public class TaskbarModelCallbacks implements
         mContainer = container;
     }
 
+    public void init(TaskbarControllers controllers) {
+        mControllers = controllers;
+    }
+
     @Override
     public void startBinding() {
         mBindInProgress = true;
@@ -161,6 +168,7 @@ public class TaskbarModelCallbacks implements
         int predictionSize = mPredictedItems.size();
         int predictionNextIndex = 0;
 
+        boolean isHotseatEmpty = true;
         for (int i = 0; i < hotseatItemInfos.length; i++) {
             hotseatItemInfos[i] = mHotseatItems.get(i);
             if (hotseatItemInfos[i] == null && predictionNextIndex < predictionSize) {
@@ -168,7 +176,14 @@ public class TaskbarModelCallbacks implements
                 hotseatItemInfos[i].screenId = i;
                 predictionNextIndex++;
             }
+            if (hotseatItemInfos[i] != null) {
+                isHotseatEmpty = false;
+            }
         }
         mContainer.updateHotseatItems(hotseatItemInfos);
+
+        mControllers.taskbarStashController.updateStateForFlag(
+                TaskbarStashController.FLAG_STASHED_IN_APP_EMPTY, isHotseatEmpty);
+        mControllers.taskbarStashController.applyState();
     }
 }