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 a477695c0932d89bccc0253d22a162a667b74ccd..958538bed697ea88465c8f66a5e059bcad33b3b9 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -348,7 +348,8 @@ class GDataFileSystem : public ProfileKeyedService {
     FileOperationCallback callback;
   };
 
-  explicit GDataFileSystem(Profile* profile);
+  explicit GDataFileSystem(Profile* profile,
+                           DocumentsServiceInterface* documents_service);
   virtual ~GDataFileSystem();
 
   // Initiates upload operation of file defined with |file_name|,
@@ -479,7 +480,7 @@ 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> gdata_uploader_;