chromeos: Destruct DriveResourceMetadata on the blocking pool

chrome/browser/chromeos/drive/drive_test_util.h

Index: chrome/browser/chromeos/drive/drive_test_util.h
diff --git a/chrome/browser/chromeos/drive/drive_test_util.h b/chrome/browser/chromeos/drive/drive_test_util.h
index 03fb3d93124f67a5e37525b77f83e49dca814200..d95a245a15f8d67ffb1354ecac836894b45c2dc9 100644
--- a/chrome/browser/chromeos/drive/drive_test_util.h
+++ b/chrome/browser/chromeos/drive/drive_test_util.h
@@ -169,9 +169,18 @@ bool LoadChangeFeed(const std::string& relative_path,
                     bool is_delta_feed,
                     int64 root_feed_changestamp);
 
-// DriveCache has private destructor, so it is impossible to delete the
-// instance directly. This method delete it correctly.
-void DeleteDriveCache(DriveCache* drive_cache);
+// Helper to destroy objects which needs Destroy() to be called on destruction.
+// Note: When using this helper, you should destruct objects before
+// BrowserThread.
+struct DestroyHelperForTests {
+  template<typename T>
+  void operator()(T* object) const {
+    if (object) {
+      object->Destroy();
+      google_apis::test_util::RunBlockingPoolTask();  // Finish destruction.
+    }
+  }
+};
 
 }  // namespace test_util
 }  // namespace drive