[heap] Decouple SpaceIterator from ObjectIterator.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 41e0727a3fbe9a634dff2bde325fd996b9951de9..a1b93c29d9c56adf15b78da9835580bcd282fdf1 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -935,6 +935,8 @@ class Space : public Malloced {
     }
   }
 
+  virtual std::unique_ptr<ObjectIterator> GetObjectIterator() = 0;
+
   void AccountCommitted(intptr_t bytes) {
     DCHECK_GE(bytes, 0);
     committed_ += bytes;
@@ -2146,6 +2148,8 @@ class PagedSpace : public Space {
   // using the high water mark.
   void ShrinkImmortalImmovablePages();
 
+  std::unique_ptr<ObjectIterator> GetObjectIterator() override;
+
  protected:
   // PagedSpaces that should be included in snapshots have different, i.e.,
   // smaller, initial pages.
@@ -2344,6 +2348,8 @@ class SemiSpace : public Space {
   iterator begin() { return iterator(anchor_.next_page()); }
   iterator end() { return iterator(anchor()); }
 
+  std::unique_ptr<ObjectIterator> GetObjectIterator() override;

[Michael Lippautz, 2016/09/27 13:53:05]

While you are here, can you move this line and the begin/end iterators above the
#ifdefs? 

(While cleaning up the heap api I made sure that #ifdef DEBUG and VERIFY_HEAP
are the last "sections" in a class decl.)

[ulan, 2016/09/27 14:10:53]

Done.

+
  private:
   void RewindPages(Page* start, int num_pages);
 
@@ -2675,6 +2681,8 @@ class NewSpace : public Space {
   iterator begin() { return to_space_.begin(); }
   iterator end() { return to_space_.end(); }
 
+  std::unique_ptr<ObjectIterator> GetObjectIterator() override;
+
  private:
   // Update allocation info to match the current to-space page.
   void UpdateAllocationInfo();
@@ -2888,6 +2896,8 @@ class LargeObjectSpace : public Space {
   iterator begin() { return iterator(first_page_); }
   iterator end() { return iterator(nullptr); }
 
+  std::unique_ptr<ObjectIterator> GetObjectIterator() override;
+
 #ifdef VERIFY_HEAP
   virtual void Verify();
 #endif