Simple Cache: stop running index file tests on Windows

net/disk_cache/simple/simple_index_file_unittest.cc

Index: net/disk_cache/simple/simple_index_file_unittest.cc
diff --git a/net/disk_cache/simple/simple_index_file_unittest.cc b/net/disk_cache/simple/simple_index_file_unittest.cc
index b75237e8d2283b706ba1f1ac1ca875b421dc602d..472c8adafacb668aefbb812cd16973cccd0d3336 100644
--- a/net/disk_cache/simple/simple_index_file_unittest.cc
+++ b/net/disk_cache/simple/simple_index_file_unittest.cc
@@ -25,6 +25,11 @@ using disk_cache::SimpleIndex;
 
 namespace disk_cache {
 
+// 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(IndexMetadataTest, Basics) {
   SimpleIndexFile::IndexMetadata index_metadata;
 
@@ -242,4 +247,6 @@ TEST_F(SimpleIndexFileTest, LoadCorruptIndex) {
   EXPECT_TRUE(load_index_result.flush_required);
 }
 
+#endif  // defined(OS_POSIX)
+
 }  // namespace disk_cache