Simple Cache: stop running index file tests on Windows

net/disk_cache/entry_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/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 2279 matching lines @@
   memset(store->key + key.size(), 'k', sizeof(store->key) - key.size());
   entry_impl->entry()->set_modified();
   entry->Close();
 
   // We have a corrupt entry. Now reload it. We should NOT read beyond the
   // allocated buffer here.
   ASSERT_NE(net::OK, OpenEntry(key, &entry));
   DisableIntegrityCheck();
 }
 
-// The simple cache backend isn't intended to work on Windows, which has very
-// different file system guarantees from Linux.
+// The Simple Cache backend requires a few guarantees from the filesystem like
+// atomic renaming of recently open files. Those guarantees are not provided in
+// general on Windows.
 #if defined(OS_POSIX)
 
 TEST_F(DiskCacheEntryTest, SimpleCacheInternalAsyncIO) {
   SetSimpleCacheMode();
   InitCache();
   InternalAsyncIO();
 }
 
 TEST_F(DiskCacheEntryTest, SimpleCacheExternalAsyncIO) {
   SetSimpleCacheMode();
@@ skipping 1137 matching lines @@
 
   // Check that we are not leaking.
   ASSERT_NE(entry, null);
   EXPECT_TRUE(
       static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
   entry->Close();
   entry = NULL;
 }
 
 #endif  // defined(OS_POSIX)