Add GetChangelist operation for Drive V2.

chrome/browser/chromeos/gdata/gdata_operations.h

Index: chrome/browser/chromeos/gdata/gdata_operations.h
diff --git a/chrome/browser/chromeos/gdata/gdata_operations.h b/chrome/browser/chromeos/gdata/gdata_operations.h
index 0784dfac21c7df2a3f1d6453cfe5017ae50e6184..f04182e66c464436521bd2f314e57c5c7fa18b49 100644
--- a/chrome/browser/chromeos/gdata/gdata_operations.h
+++ b/chrome/browser/chromeos/gdata/gdata_operations.h
@@ -17,17 +17,19 @@ namespace gdata {
 // This class performs the operation for fetching a document list.
 class GetDocumentsOperation : public GetDataOperation {
  public:
+  // |start_changestamp| specifies the starting point of change list or 0 if
+  // all changes are necessary.
+  // |url| specifies URL for documents feed fetching operation. If empty URL is
+  // passed, the default URL is used and returns the first page of the result.
+  // When non-first page result is requested, |url| should be specified.
   GetDocumentsOperation(GDataOperationRegistry* registry,
+                        const GURL& url,
                         int start_changestamp,
                         const std::string& search_string,
                         const std::string& directory_resource_id,
                         const GetDataCallback& callback);
   virtual ~GetDocumentsOperation();
 
-  // Sets |url| for document fetching operation. This URL should be set in use
-  // case when additional 'pages' of document lists are being fetched.
-  void SetUrl(const GURL& url);
-
  protected:
   // Overridden from GetDataOperation.
   virtual GURL GetURL() const OVERRIDE;