Update the received slices vector when stream is written to disk

content/browser/download/download_file_impl.h

Index: content/browser/download/download_file_impl.h
diff --git a/content/browser/download/download_file_impl.h b/content/browser/download/download_file_impl.h
index 61f1f4d90bb054a524b32e402f78111c7d1de5a0..f25b4e60013c929f606c1dd2a6139acfa6099204 100644
--- a/content/browser/download/download_file_impl.h
+++ b/content/browser/download/download_file_impl.h
@@ -109,9 +109,12 @@ class CONTENT_EXPORT DownloadFileImpl : public DownloadFile {
     ByteStreamReader* stream_reader() const { return stream_reader_.get(); }
     int64_t offset() const { return offset_; }
     int64_t length() const { return length_; }
+    void set_length(int64_t length) { length_ = length; }
     int64_t bytes_written() const { return bytes_written_; }
     bool is_finished() const { return finished_; }
     void set_finished(bool finish) { finished_ = finish; }
+    size_t index() { return index_; }
+    void set_index(size_t index) { index_ = index; }
 
    private:
     // Starting position for the stream to write to disk.
@@ -129,6 +132,10 @@ class CONTENT_EXPORT DownloadFileImpl : public DownloadFile {
     // disk.
     bool finished_;
 
+    // The slice index in the |received_slices_| vector. A slice was created
+    // once the stream started writing data to the target file.
+    size_t index_;
+
     // The stream through which data comes.
     std::unique_ptr<ByteStreamReader> stream_reader_;
 
@@ -183,6 +190,11 @@ class CONTENT_EXPORT DownloadFileImpl : public DownloadFile {
   // Register callback and start to read data from the stream.
   void RegisterAndActivateStream(SourceStream* source_stream);
 
+  // Adds a new slice to |received_slices_| and update the existing entries in
+  // |source_streams_| as their lengths will change.
+  // TODO(qinmin): add a test for this function.
+  void AddNewSlice(int64_t offset, int64_t length);
+
   // Return the total valid bytes received in the target file.
   // If the file is a sparse file, return the total number of valid bytes.
   // Otherwise, return the current file size.