Rearrange Should*Download delegate calls to be more useful and intuitive.

content/browser/download/download_manager.cc

Index: content/browser/download/download_manager.cc
diff --git a/content/browser/download/download_manager.cc b/content/browser/download/download_manager.cc
index 5cdf0065083262566f8ca7e91ae9278dbcc77af0..b45ac95db6e2ed7c8246f7ae38cdf0b682b975a9 100644
--- a/content/browser/download/download_manager.cc
+++ b/content/browser/download/download_manager.cc
@@ -483,6 +483,10 @@ void DownloadManager::MaybeCompleteDownload(DownloadItem* download) {
   DCHECK(download->db_handle() != DownloadItem::kUninitializedHandle);
   DCHECK_EQ(1u, history_downloads_.count(download->db_handle()));
 
+  // Give the delegate a chance to override.
+  if (!delegate_->ShouldCompleteDownload(download))
+    return;
+
   VLOG(20) << __FUNCTION__ << "()" << " executing: download = "
            << download->DebugString(false);