metrics: fix memory leaks in unittest.

This fixes the memory leaks exposed in unittest.

BUG=chromium:408309
TEST=The memory leak related to |sender_| is gone.

Change-Id: I92970d0560f6ccd1ccd7f5022ece8cc5eba4a674
Reviewed-on: https://chromium-review.googlesource.com/214578
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
4 files changed
tree: 633de7c654780d5c6a37d830c13f1b0c8b3b982e
  1. metrics/