Fixing notification of the docked stack state for the current user.

- When there are multiple users, ensure that we check that there are
  tasks in the docked stack for each user (instead of just the presence
  of the docked stack) and re-notify listeners of the state of the
  docked stack when the user is switched.

Change-Id: I911c4a32db187f9cd29d462309bd0cf7febb1993

packages/SystemUI/src/com/android/systemui/recents/misc/SystemServicesProxy.java

@@ -378,13 +378,19 @@ public class SystemServicesProxy {
         ActivityManager.StackInfo stackInfo = null;
         try {
             stackInfo = mIam.getStackInfo(DOCKED_STACK_ID);
-            if (stackInfo != null && stackInfo.userId != getCurrentUser()) {
-                return false;
-            }
         } catch (RemoteException e) {
             e.printStackTrace();
         }
-        return stackInfo != null;
+
+        if (stackInfo != null) {
+            int userId = getCurrentUser();
+            boolean hasUserTask = false;
+            for (int i = stackInfo.taskUserIds.length - 1; i >= 0 && !hasUserTask; i--) {
+                hasUserTask = (stackInfo.taskUserIds[i] == userId);
+            }
+            return hasUserTask;
+        }
+        return false;
     }
 
     /**

services/core/java/com/android/server/wm/WindowManagerService.java

@@ -5349,9 +5349,31 @@ public class WindowManagerService extends IWindowManager.Stub
                 rebuildAppWindowListLocked(displayContent);
             }
             mWindowPlacerLocked.performSurfacePlacement();
+
+            // Notify whether the docked stack exists for the current user
+            getDefaultDisplayContentLocked().mDividerControllerLocked
+                    .notifyDockedStackExistsChanged(hasDockedTasksForUser(newUserId));
         }
     }
 
+    /**
+     * Returns whether there is a docked task for the current user.
+     */
+    boolean hasDockedTasksForUser(int userId) {
+        final TaskStack stack = mStackIdToStack.get(DOCKED_STACK_ID);
+        if (stack == null) {
+            return false;
+        }
+
+        final ArrayList<Task> tasks = stack.getTasks();
+        boolean hasUserTask = false;
+        for (int i = tasks.size() - 1; i >= 0 && !hasUserTask; i--) {
+            final Task task = tasks.get(i);
+            hasUserTask = (task.mUserId == userId);
+        }
+        return hasUserTask;
+    }
+
     /* Called by WindowState */
     boolean isCurrentProfileLocked(int userId) {
         if (userId == mCurrentUserId) return true;