Do not DCHECK on SimpleCache deletion-while-closing.

net/disk_cache/backend_unittest.cc

Index: net/disk_cache/backend_unittest.cc
diff --git a/net/disk_cache/backend_unittest.cc b/net/disk_cache/backend_unittest.cc
index bb313ed39d2075d060f0f88ebdeb370d71143d5b..9969e3e4985caca10aae046d48f93bb4d7718fe0 100644
--- a/net/disk_cache/backend_unittest.cc
+++ b/net/disk_cache/backend_unittest.cc
@@ -3481,3 +3481,13 @@ TEST_F(DiskCacheBackendTest, SimpleCacheEnumerationDestruction) {
   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.

[jkarlin, 2014/10/30 19:19:24]

Append the bug that this CL fixes to the test comment.

[jkarlin, 2014/10/30 19:19:24]

Does this flake at least say 20% of the time?  It needs to flake fairly  often
to be noticed.  How hard would it be to make this test work 100% of the time?

[gavinp, 2014/10/31 13:55:54]

I get a 100% failure rate on 100 iterations on my Mac, and that runs in 380ms.
I'm calling that acceptable for now. I'm a bit concerned about windows, so I'll
watch try bots.

[gavinp, 2014/10/31 13:55:54]

Done.

+TEST_F(DiskCacheBackendTest, SimpleCacheDeleteQuickly) {
+  SetSimpleCacheMode();
+  InitCache();
+  cache_.reset();
+  EXPECT_TRUE(CleanupCacheDir());
+}