Added ActivityManager API and AM command to resize a task.

Also fixed issue with ActivityStackSupervisor.moveTaskToStackLocked()
functionality not working correctly.

Change-Id: Ia13f1e92a7c59ce6543c226533ac8ea623488290
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index a9b26e2..b8f26c9 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -72,6 +72,19 @@
         mService.mTaskIdToTask.delete(mTaskId);
     }
 
+    void moveTaskToStack(TaskStack stack, boolean toTop) {
+        if (stack == mStack) {
+            return;
+        }
+        if (DEBUG_STACK) Slog.i(TAG, "moveTaskToStack: removing taskId=" + mTaskId
+                + " from stack=" + mStack);
+        EventLog.writeEvent(EventLogTags.WM_TASK_REMOVED, mTaskId, "removeTask");
+        if (mStack != null) {
+            mStack.removeTask(this);
+        }
+        stack.addTask(this, toTop);
+    }
+
     boolean removeAppToken(AppWindowToken wtoken) {
         boolean removed = mAppTokens.remove(wtoken);
         if (mAppTokens.size() == 0) {