Refactor the functions related to collecting code statistics to a new class.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 29a0b66d9de1ae4ea8b4614ba970eaaa1e68eb52..28f1e1cdbb0e5abfa8ef55bf004c05903168d754 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2239,11 +2239,6 @@ class PagedSpace : public Space {
   // The dummy page that anchors the linked list of pages.
   Page* anchor() { return &anchor_; }
 
-  // Collect code size related statistics
-  void CollectCodeStatistics();
-
-  // Reset code size related statistics
-  static void ResetCodeAndMetadataStatistics(Isolate* isolate);
 
 #ifdef VERIFY_HEAP
   // Verify integrity of this space.