Fix temp dir cleanup in SessionCleanupCookieManagerTest.

The ScopedTempDir must outlive anything that holds file(s) open within
it; otherwise, it is unable to delete itself.

BUG=546640
R=cduvall@chromium.org

Change-Id: Ifc33562cffe7d2f240311f421530e747e16afa9b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890059
Auto-Submit: Greg Thompson <grt@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710814}
diff --git a/services/network/cookie_manager_unittest.cc b/services/network/cookie_manager_unittest.cc
index 5c7b251..f89e6a3 100644
--- a/services/network/cookie_manager_unittest.cc
+++ b/services/network/cookie_manager_unittest.cc
@@ -338,6 +338,7 @@
         &CookieManagerTest::OnConnectionError, base::Unretained(this)));
   }
 
+  base::ScopedTempDir temp_dir_;
   base::test::TaskEnvironment task_environment_;
 
  private:
@@ -2237,7 +2238,6 @@
  private:
   const scoped_refptr<base::SequencedTaskRunner> background_task_runner_ =
       base::CreateSequencedTaskRunner({base::ThreadPool(), base::MayBlock()});
-  base::ScopedTempDir temp_dir_;
 };
 
 TEST_F(SessionCleanupCookieManagerTest, PersistSessionCookies) {