title: Issue with StorageAccessFramework and DownloadManager
body: <p>I have one problem. I am developing some Streaming/Video downloading app. 
  I am using <a href="http://developer.android.com/reference/android/app/DownloadManager.Request.html" rel="noreferrer" title="DownloadManager docs">DownloadManager</a> for video downloads.</p>
  
  <p>Request is to offer user's to pick destination for saving (SDCard or internal phone storage).</p>
  
  <p>I have problems on Lollipop with <a href="https://developer.android.com/guide/topics/providers/document-provider.html" rel="noreferrer">SAF</a> and DownloadManager.</p>
  
  <p>I am offering to the user to pick directory for storing files I download:</p>
  
  <pre><code>Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
  startActivityForResult(intent, REQUEST_CODE_FOR_DESTINATION);
  </code></pre>
  
  <p>and in onActivityResult i am getting it via</p>
  
  <pre><code>Uri treeUri = data.getData();
  DocumentFile destinationDirUri = DocumentFile.fromTreeUri(this, treeUri);
  </code></pre>
  
  <p>Now, I need to set this destination as destination to DownloadManager.Request</p>
  
  <pre><code>Request request = new DownloadManager.Request(Uri.parse(getDownloadUrl()));
  request.setTitle(downloadInfo.getTitle());
  request.allowScanningByMediaScanner();
  request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
  request.setDestinationUri(destinationDirUri);
  </code></pre>
  
  <p>After I select "Downloads/video" directory, and perform</p>
  
  <pre><code>DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
  downloadManager.enqueue(request);
  </code></pre>
  
  <p>I am getting </p>
  
  <pre><code>E/RecordDownloader﹕ Error while retrieving download infos    
  W/System.err﹕ java.lang.IllegalArgumentException: Not a file URI: content://com.android.externalstorage.documents/tree/primary%3ADownload%2Fvideo
  W/System.err﹕ at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:167)
  W/System.err﹕ at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:137)
  W/System.err﹕ at android.content.ContentProviderProxy.insert(ContentProviderNative.java:475)
  W/System.err﹕ at android.content.ContentResolver.insert(ContentResolver.java:1207)
  W/System.err﹕ at android.app.DownloadManager.enqueue(DownloadManager.java:946)
  W/System.err﹕ at ch.teleboy.download.RecordDownloader.enqueueDownloadRequest(RecordDownloader.java:102)
  W/System.err﹕ at ch.teleboy.download.RecordDownloader.access$300(RecordDownloader.java:48)
  W/System.err﹕ at ch.teleboy.download.RecordDownloader$DownloaderTask.run(RecordDownloader.java:191)
  W/System.err﹕ at java.lang.Thread.run(Thread.java:818)
  </code></pre>
  
  <p>If I try to write some file to selected location, it works.</p>
  
  <pre><code>DocumentFile newFile = destinationDirUri.createFile("text/plain", "test.txt");
  OutputStream out = getContentResolver().openOutputStream(newFile.getUri());
  out.write("Some dummy text...".getBytes());
  out.close()
  </code></pre>
  
  <p>Any suggestions? </p>