drive: Return cancel closure from FileSystem::GetFileContent

chrome/browser/chromeos/drive/sync_client.h

Index: chrome/browser/chromeos/drive/sync_client.h
diff --git a/chrome/browser/chromeos/drive/sync_client.h b/chrome/browser/chromeos/drive/sync_client.h
index a68458eadf8d74849d1fa96286267c6b4c962410..a8f6d1b3a57ba8d7bec1b6afb0fd00e5375072e2 100644
--- a/chrome/browser/chromeos/drive/sync_client.h
+++ b/chrome/browser/chromeos/drive/sync_client.h
@@ -101,7 +101,7 @@ class SyncClient {
     SyncTask();
     ~SyncTask();
     SyncState state;
-    base::Closure task;
+    base::Callback<base::Closure()> task;
     bool should_run_again;
     base::Closure cancel_closure;
   };
@@ -132,13 +132,6 @@ class SyncClient {
   // Adds fetch tasks.
   void AddFetchTasks(const std::vector<std::string>* local_ids);
 
-  // Used as GetFileContentInitializedCallback.
-  void OnGetFileContentInitialized(
-      FileError error,
-      scoped_ptr<ResourceEntry> entry,
-      const base::FilePath& local_cache_file_path,
-      const base::Closure& cancel_download_closure);
-
   // Erases the task and returns true if task is completed.
   bool OnTaskComplete(SyncType type, const std::string& local_id);