title: How to update the TabSpec
body: <p>I have 3 tabs contain different contents. They loads content from Internet. I use 3 AsyncTasks to do it. 
  At the beginning, 3 tabs show 3 ProgressBar. I want that everytime one task finishs, it updates the TabSpec and hide the ProgressBar. 
  <strong>The problem is I don't know how to update the tab spec.</strong></p>
  
  <p>This is my snippet to create TabHost at the beginnig.</p>
  
  <pre><code>    final List&lt;View&gt; containerList = new ArrayList&lt;View&gt;();
      for(int i = 0; i &lt; 4; ++i) {
          final LinearLayout layout = new LinearLayout(this);
          final ProgressBar progressBar = new ProgressBar(this);
          progressBar.setVisibility(View.VISIBLE);
          layout.addView(progressBar);            
      }
  
      // Prepare labels and icons.        
      final List&lt;String&gt; tabLabels = Arrays.asList(getResources().getStringArray(R.array.destination_tab_labels));       
      // TODO Prepare icons here later.
  
      // Populate tabs' contents.
      final TabHost tabHost = getTabHost();
      for(final String label : tabLabels) {
          final TabSpec tab = tabHost.newTabSpec(label);
          tab.setContent(new TabContentFactory() {
              @Override
              public View createTabContent(final String tag) {
                  // Return ListView here later.
                  return containerList.get(i++);
              }
          });
          //TODO Add icon here later.
          tab.setIndicator(label);
          tabHost.addTab(tab);
      }
  </code></pre>