[heap] Sort sweep pages list by free memory.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 532c9b2e878f2cad7e1a3dc3d2c67ae6443d5490..5c4a70a81be2033a1cc0abb285d4dd09dbdd6bea 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2116,10 +2116,6 @@ class PagedSpace : public Space {
   // It returns true when sweeping is completed and false otherwise.
   bool EnsureSweeperProgress(intptr_t size_in_bytes);
 
-  void set_end_of_unswept_pages(Page* page) { end_of_unswept_pages_ = page; }
-
-  Page* end_of_unswept_pages() { return end_of_unswept_pages_; }
-
   Page* FirstPage() { return anchor_.next_page(); }
   Page* LastPage() { return anchor_.prev_page(); }
 
@@ -2203,11 +2199,6 @@ class PagedSpace : public Space {
   // Normal allocation information.
   AllocationInfo allocation_info_;
 
-  // The sweeper threads iterate over the list of pointer and data space pages
-  // and sweep these pages concurrently. They will stop sweeping after the
-  // end_of_unswept_pages_ page.
-  Page* end_of_unswept_pages_;
-
   // Mutex guarding any concurrent access to the space.
   base::Mutex space_mutex_;