Merge 32898 - Fixes extension packing codepath that was hitting a race condit...

chrome/browser/extensions/pack_extension_job.h

Index: chrome/browser/extensions/pack_extension_job.h
===================================================================
--- chrome/browser/extensions/pack_extension_job.h	(revision 32908)
+++ chrome/browser/extensions/pack_extension_job.h	(working copy)
@@ -29,6 +29,10 @@
                    const FilePath& root_directory,
                    const FilePath& key_file);
 
+  // Starts the packing thread job. See http://crbug.com/27944 for more details
+  // on why this function is needed.
+  void Start();
+
   // The client should call this when it is destroyed to prevent
   // PackExtensionJob from attempting to access it.
   void ClearClient();