Do not DCHECK on SimpleCache deletion-while-closing.

net/disk_cache/backend_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/basictypes.h"
 #include "base/files/file_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/port.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 3463 matching lines @@
 
   scoped_ptr<TestIterator> iter = CreateIterator();
   disk_cache::Entry* entry = NULL;
   ASSERT_EQ(net::OK, iter->OpenNextEntry(&entry));
   EXPECT_TRUE(entry);
   disk_cache::ScopedEntryPtr entry_closer(entry);
 
   cache_.reset();
   // This test passes if we don't leak memory.
 }
+
+// Tests that a SimpleCache doesn't crash when files are deleted very quickly
+// after closing.
+// NOTE: IF THIS TEST IS FLAKY THEN IT IS FAILING. See https://crbug.com/416940
+TEST_F(DiskCacheBackendTest, SimpleCacheDeleteQuickly) {
+  SetSimpleCacheMode();
+  for (int i = 0; i < 100; ++i) {
+    InitCache();
+    cache_.reset();
+    EXPECT_TRUE(CleanupCacheDir());
+  }
+}