Add new UMA stats for parallelizable download

content/browser/download/mock_download_file.h

Index: content/browser/download/mock_download_file.h
diff --git a/content/browser/download/mock_download_file.h b/content/browser/download/mock_download_file.h
index 81d3b260ef61f6929fcdaf505b42e2ea8e4c3dd5..c45e0dd56fae2a58033305c34ae93d266279bdfc 100644
--- a/content/browser/download/mock_download_file.h
+++ b/content/browser/download/mock_download_file.h
@@ -28,9 +28,10 @@ class MockDownloadFile : public DownloadFile {
   virtual ~MockDownloadFile();
 
   // DownloadFile functions.
-  MOCK_METHOD2(Initialize,
+  MOCK_METHOD3(Initialize,
                void(const InitializeCallback&,
-                    const DownloadItem::ReceivedSlices& received_slices));
+                    const DownloadItem::ReceivedSlices& received_slices,
+                    bool is_parallelizable));
   void AddByteStream(std::unique_ptr<ByteStreamReader> stream_reader,
                      int64_t offset,
                      int64_t length) override;