diff --git a/download_action.h b/download_action.h
index 020aa9c..e6099f9 100644
--- a/download_action.h
+++ b/download_action.h
@@ -81,7 +81,29 @@
 
   HttpFetcher* http_fetcher() { return http_fetcher_.get(); }
 
+  // Returns the p2p file id for the file being written or the empty
+  // string if we're not writing to a p2p file.
+  std::string p2p_file_id() { return p2p_file_id_; };
+
  private:
+  // Closes the file descriptor for the p2p file being written and
+  // clears |p2p_file_id_| to indicate that we're no longer sharing
+  // the file. If |delete_p2p_file| is True, also deletes the file.
+  // If there is no p2p file descriptor, this method does nothing.
+  void CloseP2PSharingFd(bool delete_p2p_file);
+
+  // Starts sharing the p2p file. Must be called before
+  // WriteToP2PFile(). Returns True if this worked.
+  bool SetupP2PSharingFd();
+
+  // Writes |length| bytes of payload from |data| into |file_offset|
+  // of the p2p file. Also does sanity checks; for example ensures we
+  // don't end up with a file with holes in it.
+  //
+  // This method does nothing if SetupP2PSharingFd() hasn't been
+  // called or if CloseP2PSharingFd() has been called.
+  void WriteToP2PFile(const char *data, size_t length, off_t file_offset);
+
   // The InstallPlan passed in
   InstallPlan install_plan_;
 
@@ -108,6 +130,17 @@
   DownloadActionDelegate* delegate_;
   uint64_t bytes_received_;
 
+  // The file-id for the file we're sharing or the empty string
+  // if we're not using p2p to share.
+  std::string p2p_file_id_;
+
+  // The file descriptor for the p2p file used for caching the payload or -1
+  // if we're not using p2p to share.
+  int p2p_sharing_fd_;
+
+  // Set to |false| if p2p file is not visible.
+  bool p2p_visible_;
+
   DISALLOW_COPY_AND_ASSIGN(DownloadAction);
 };