AU: Update status to DOWNLOADING only after receiving some bytes from server.

update_attempter.h

Index: update_attempter.h
diff --git a/update_attempter.h b/update_attempter.h
index 19933219282184f31f15ee6710b7bfa0d8a9d20a..0f5d605a5c56c14c9c37ce6e7baaa5e37b73fb4f 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -87,7 +87,8 @@ class UpdateAttempter : public ActionProcessorDelegate,
   // UPDATED_NEED_REBOOT. Returns true on sucess, false otherwise.
   bool RebootIfNeeded();
 
-  // DownloadActionDelegate method
+  // DownloadActionDelegate methods
+  void SetDownloadStatus(bool active);
   void BytesReceived(uint64_t bytes_received, uint64_t total);
 
  private:
@@ -152,6 +153,10 @@ class UpdateAttempter : public ActionProcessorDelegate,
   // The process priority management timeout source.
   GSource* manage_priority_source_;
 
+  // Set to true if an update download is active (and BytesReceived
+  // will be called), set to false otherwise.
+  bool download_active_;
+
   // For status:
   UpdateStatus status_;
   double download_progress_;