Created an interface for DownloadFile, for use in unit tests.

content/browser/download/download_file_manager.h

Index: content/browser/download/download_file_manager.h
diff --git a/content/browser/download/download_file_manager.h b/content/browser/download/download_file_manager.h
index bf6e07beed78c91c2d7e7215b2e970b8ffd8c20d..2f5936971c8d2c8dc95e5c443f2240daa966c5ab 100644
--- a/content/browser/download/download_file_manager.h
+++ b/content/browser/download/download_file_manager.h
@@ -127,6 +127,14 @@ class CONTENT_EXPORT DownloadFileManager
     return downloads_.size();
   }
 
+ protected:
+   // Creates a new DownloadFile.
+   // Used only for testing, to create a MockDownloadFile instead.
+  DownloadFile* NewDownloadFile(
+      DownloadCreateInfo* info,
+      const DownloadRequestHandle& request_handle,
+      DownloadManager* download_manager);

[Randy Smith (Not in Mondays), 2011/11/10 21:58:43]

I don't think that this is used in this CL?  I don't think I have objections to
it, but I'd like to see it combined with its use cases to judge that.  Willing
to pull it out and put it in in the first CL that uses it?

[ahendrickson, 2011/11/13 00:50:21]

Done.

+
  private:
   friend class base::RefCountedThreadSafe<DownloadFileManager>;
   friend class DownloadManagerTest;