Fix and re-enable PrerenderTaskManager test

chrome/browser/task_manager/task_manager.h

Index: chrome/browser/task_manager/task_manager.h
diff --git a/chrome/browser/task_manager/task_manager.h b/chrome/browser/task_manager/task_manager.h
index eb62db1eb048f5276701be8997053a5352d16fb7..9517a9e735ebac0d46563695f110d191a7b20294 100644
--- a/chrome/browser/task_manager/task_manager.h
+++ b/chrome/browser/task_manager/task_manager.h
@@ -306,6 +306,9 @@ class TaskManagerModel : public base::RefCountedThreadSafe<TaskManagerModel> {
   // changes to the model.
   void ModelChanged();
 
+   // Updates the values for all rows.
+  void Refresh();
+
   void NotifyResourceTypeStats(
         base::ProcessId renderer_id,
         const WebKit::WebCache::ResourceTypeStats& stats);
@@ -450,9 +453,6 @@ class TaskManagerModel : public base::RefCountedThreadSafe<TaskManagerModel> {
   // Callback from the timer to refresh. Invokes Refresh() as appropriate.
   void RefreshCallback();
 
-   // Updates the values for all rows.
-  void Refresh();
-
   void RefreshVideoMemoryUsageStats();
 
   // Returns the network usage (in bytes per seconds) for the specified