[heap] Base number of compaction tasks on live memory and compaction speed.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 18a6a0e65fac6189098fe993c79e9c0fa254d6c8..3ba901ec33bb896946dfd7e18dea2189f1d9b6ec 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2857,7 +2857,9 @@ class CompactionSpaceCollection : public Malloced {
  public:
   explicit CompactionSpaceCollection(Heap* heap)
       : old_space_(heap, OLD_SPACE, Executability::NOT_EXECUTABLE),
-        code_space_(heap, CODE_SPACE, Executability::EXECUTABLE) {}
+        code_space_(heap, CODE_SPACE, Executability::EXECUTABLE),
+        duration_(0.0),
+        bytes_compacted_(0) {}
 
   CompactionSpace* Get(AllocationSpace space) {
     switch (space) {
@@ -2872,9 +2874,21 @@ class CompactionSpaceCollection : public Malloced {
     return nullptr;
   }
 
+  void ReportCompactionProgress(double duration, intptr_t bytes_compacted) {
+    duration_ += duration;
+    bytes_compacted_ += bytes_compacted;
+  }
+
+  double duration() const { return duration_; }
+  intptr_t bytes_compacted() const { return bytes_compacted_; }
+
  private:
   CompactionSpace old_space_;
   CompactionSpace code_space_;
+
+  // Book keeping.
+  double duration_;
+  intptr_t bytes_compacted_;
 };