Use a DownloadRequestHandle pointer in construction to allow mocking for tests.

content/browser/download/download_file.h

Index: content/browser/download/download_file.h
diff --git a/content/browser/download/download_file.h b/content/browser/download/download_file.h
index d7795c716e1a4d38122e00d23e08a36b2b536f85..bb334a5726d49fdeca654f54c202cc9992600429 100644
--- a/content/browser/download/download_file.h
+++ b/content/browser/download/download_file.h
@@ -26,8 +26,9 @@ class ResourceDispatcherHost;
 // cancelled, the DownloadFile is destroyed.
 class CONTENT_EXPORT DownloadFile : public BaseFile {
  public:
+  // Takes ownership of the object pointed to by |request_handle|.
   DownloadFile(const DownloadCreateInfo* info,
-               const DownloadRequestHandle& request_handle,
+               DownloadRequestHandleInterface* request_handle,
                DownloadManager* download_manager);
   virtual ~DownloadFile();
 
@@ -67,7 +68,7 @@ class CONTENT_EXPORT DownloadFile : public BaseFile {
 
   // The handle to the request information.  Used for operations outside the
   // download system, specifically canceling a download.
-  DownloadRequestHandle request_handle_;
+  scoped_ptr<DownloadRequestHandleInterface> request_handle_;
 
   // DownloadManager this download belongs to.
   scoped_refptr<DownloadManager> download_manager_;