Make document service an interface

chrome/browser/chromeos/gdata/gdata_file_system.h

Index: chrome/browser/chromeos/gdata/gdata_file_system.h
diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.h b/chrome/browser/chromeos/gdata/gdata_file_system.h
index bb6ed7266e1af45c419cb1d88aa4dd2a66e96a76..f0c6e420b203e932953820ad92d975e4d1afb65d 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -365,6 +365,10 @@ class GDataFileSystem : public ProfileKeyedService {
   void ResumeUpload(const ResumeUploadParams& params,
                     const ResumeUploadOperationCallback& callback);
 
+  // Only used by tests to inject a mock documents service.
+  void ReplaceDocumentsService(
+      scoped_ptr<DocumentsServiceInterface> documents_service);
+
   // Unsafe (unlocked) version of the function above.
   void UnsafeFindFileByPath(const FilePath& file_path,
                             scoped_refptr<FindFileDelegate> delegate);
@@ -456,7 +460,7 @@ class GDataFileSystem : public ProfileKeyedService {
   Profile* profile_;
 
   // The document service for the GDataFileSystem.
-  scoped_ptr<DocumentsService> documents_service_;
+  scoped_ptr<DocumentsServiceInterface> documents_service_;
 
   // File content uploader.
   scoped_ptr<GDataUploader> uploader_;