Ensure that calls to EnableGrowthControl/DisableGrowthControl does not reset the last_usage_ value …

runtime/vm/pages.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_PAGES_H_
 #define VM_PAGES_H_
 
 #include "vm/freelist.h"
 #include "vm/globals.h"
 #include "vm/lockers.h"
@@ skipping 123 matching lines @@
   // Should be called after each collection to update the controller state.
   void EvaluateGarbageCollection(SpaceUsage before,
                                  SpaceUsage after,
                                  int64_t start, int64_t end);
 
   int64_t last_code_collection_in_us() { return last_code_collection_in_us_; }
   void set_last_code_collection_in_us(int64_t t) {
     last_code_collection_in_us_ = t;
   }
 
-  void Enable(SpaceUsage current) {
+  void set_last_usage(SpaceUsage current) {
     last_usage_ = current;
+  }
+
+  void Enable() {
     is_enabled_ = true;
   }
   void Disable() {
     is_enabled_ = false;
   }
   bool is_enabled() {
     return is_enabled_;
   }
 
  private:
@@ skipping 102 matching lines @@
 
   // Checks if enough time has elapsed since the last attempt to collect
   // code.
   bool ShouldCollectCode();
 
   // Collect the garbage in the page space using mark-sweep.
   void MarkSweep(bool invoke_api_callbacks);
 
   void StartEndAddress(uword* start, uword* end) const;
 
+  void InitGrowthControl() {
+    page_space_controller_.set_last_usage(usage_);
+    page_space_controller_.Enable();
+  }
+
   void SetGrowthControlState(bool state) {
     if (state) {
-      page_space_controller_.Enable(usage_);
+      page_space_controller_.Enable();
     } else {
       page_space_controller_.Disable();
     }
   }
 
   bool GrowthControlState() {
     return page_space_controller_.is_enabled();
   }
 
   bool NeedsExternalGC() const {
@@ skipping 167 matching lines @@
   friend class HeapIterationScope;
   friend class PageSpaceController;
   friend class SweeperTask;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PageSpace);
 };
 
 }  // namespace dart
 
 #endif  // VM_PAGES_H_