doubly-linked free-lists for thread caches and page heaps

third_party/tcmalloc/chromium/src/thread_cache.cc

Index: third_party/tcmalloc/chromium/src/thread_cache.cc
diff --git a/third_party/tcmalloc/chromium/src/thread_cache.cc b/third_party/tcmalloc/chromium/src/thread_cache.cc
index b00e3b40f50a94775561cae571293beda6b7d493..a951f77c4e0a5c3c0c4a43fdb0d399800d7e908d 100644
--- a/third_party/tcmalloc/chromium/src/thread_cache.cc
+++ b/third_party/tcmalloc/chromium/src/thread_cache.cc
@@ -153,7 +153,10 @@ void* ThreadCache::FetchFromCentralCache(size_t cl, size_t byte_size) {
   ASSERT((start == NULL) == (fetch_count == 0));
   if (--fetch_count >= 0) {
     size_ += byte_size * fetch_count;
-    list->PushRange(fetch_count, SLL_Next(start), end);
+    // Pop the top of the list and add the rest to the freelist.
+    void *second = start;
+    start = FL_Pop(&second);
+    list->PushRange(fetch_count, second, end);
   }
 
   // Increase max length slowly up to batch_size.  After that,