Do not invoke onProgressUpdate if the task is canceled.

Bug #2734382

Change-Id: I8d507ae72af2f6dfe66598fb9090872520111a6b

core/java/android/os/AsyncTask.java

@@ -401,6 +401,9 @@ public abstract class AsyncTask<Params, Progress, Result> {
      * publish updates on the UI thread while the background computation is
      * still running. Each call to this method will trigger the execution of
      * {@link #onProgressUpdate} on the UI thread.
+     * 
+     * {@link #onProgressUpdate} will note be called if the task has been
+     * canceled.
      *
      * @param values The progress values to update the UI with.
      *
@@ -408,8 +411,10 @@ public abstract class AsyncTask<Params, Progress, Result> {
      * @see #doInBackground
      */
     protected final void publishProgress(Progress... values) {
-        sHandler.obtainMessage(MESSAGE_POST_PROGRESS,
-                new AsyncTaskResult<Progress>(this, values)).sendToTarget();
+        if (!isCancelled()) {
+            sHandler.obtainMessage(MESSAGE_POST_PROGRESS,
+                    new AsyncTaskResult<Progress>(this, values)).sendToTarget();
+        }
     }
 
     private void finish(Result result) {