Make the download's response headers available in the DownloadItem

content/public/test/fake_download_item.h

Index: content/public/test/fake_download_item.h
diff --git a/content/public/test/fake_download_item.h b/content/public/test/fake_download_item.h
index e26f0d8c1872bb0dbaad31ec11aaeed0d268ab47..369e1a84c3dee8da9c36f030758b0c6434da6d2d 100644
--- a/content/public/test/fake_download_item.h
+++ b/content/public/test/fake_download_item.h
@@ -63,6 +63,9 @@ class FakeDownloadItem : public DownloadItem {
   void SetState(const DownloadState& state);
   DownloadState GetState() const override;
 
+  void SetResponseCode(int response_code);
+  int GetResponseCode() const override;
+
   void SetMimeType(const std::string& mime_type);
   std::string GetMimeType() const override;
 
@@ -149,6 +152,7 @@ class FakeDownloadItem : public DownloadItem {
   // MAX_DOWNLOAD_STATE is used as the uninitialized state.
   DownloadState download_state_ =
       DownloadItem::DownloadState::MAX_DOWNLOAD_STATE;
+  int response_code_ = 0;
   std::string mime_type_;
   GURL original_url_;
   DownloadInterruptReason last_reason_ =