Implement polling part of DriveFileSyncService

chrome/browser/sync_file_system/drive_file_sync_client.h

Index: chrome/browser/sync_file_system/drive_file_sync_client.h
diff --git a/chrome/browser/sync_file_system/drive_file_sync_client.h b/chrome/browser/sync_file_system/drive_file_sync_client.h
index 48043d69bcc80bfe75adc49ee2ef2236e87d00c3..f801a1d6cb9ce30272626c223f339ff422237abf 100644
--- a/chrome/browser/sync_file_system/drive_file_sync_client.h
+++ b/chrome/browser/sync_file_system/drive_file_sync_client.h
@@ -15,6 +15,7 @@
 #include "chrome/browser/google_apis/drive_upload_error.h"
 #include "chrome/browser/google_apis/gdata_errorcode.h"
 #include "chrome/browser/google_apis/gdata_wapi_parser.h"
+#include "chrome/browser/google_apis/gdata_wapi_url_generator.h"
 
 class GURL;
 class Profile;
@@ -150,6 +151,12 @@ class DriveFileSyncClient : public base::NonThreadSafe,
                   const std::string& remote_file_md5,
                   const GDataErrorCallback& callback);
 
+  static std::string OriginToDirectoryTitle(const GURL& origin);
+  static GURL DirectoryTitleToOrigin(const std::string& title);
+
+  // Convers |resource_id| to corresponing resource link.
+  GURL ResourceIdToResourceLink(const std::string& resource_id) const;
+
  private:
   friend class DriveFileSyncClientTest;
   friend class DriveFileSyncServiceTest;
@@ -237,6 +244,7 @@ class DriveFileSyncClient : public base::NonThreadSafe,
 
   scoped_ptr<google_apis::DriveServiceInterface> drive_service_;
   scoped_ptr<google_apis::DriveUploaderInterface> drive_uploader_;
+  google_apis::GDataWapiUrlGenerator url_generator_;
 
   DISALLOW_COPY_AND_ASSIGN(DriveFileSyncClient);
 };