Add Heap::isolate_ to simplify code.

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/ring_buffer.h"
@@ skipping 96 matching lines @@
   RingBuffer<Entry, kHistoryLength> history_;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(PageSpaceGarbageCollectionHistory);
 };
 
 
 // PageSpaceController controls the heap size.
 class PageSpaceController {
  public:
-  PageSpaceController(int heap_growth_ratio,
+  // The heap is passed in for recording stats only. The controller does not
+  // invoke GC by itself.
+  PageSpaceController(Heap* heap,
+                      int heap_growth_ratio,
                       int heap_growth_max,
                       int garbage_collection_time_ratio);
   ~PageSpaceController();
 
   // Returns whether growing to 'after' should trigger a GC.
   // This method can be called before allocation (e.g., pretenuring) or after
   // (e.g., promotion), as it does not change the state of the controller.
   bool NeedsGarbageCollection(SpaceUsage after) const;
 
   // Should be called after each collection to update the controller state.
@@ skipping 11 matching lines @@
     is_enabled_ = true;
   }
   void Disable() {
     is_enabled_ = false;
   }
   bool is_enabled() {
     return is_enabled_;
   }
 
  private:
+  Heap* heap_;
+
   bool is_enabled_;
 
   // Usage after last evaluated GC or last enabled.
   SpaceUsage last_usage_;
 
   // Pages of capacity growth allowed before next GC is advised.
   intptr_t grow_heap_;
 
   // If the garbage collector was not able to free more than heap_growth_ratio_
   // memory, then the heap is grown. Otherwise garbage collection is performed.
@@ skipping 161 matching lines @@
   intptr_t collections_;
 
   friend class PageSpaceController;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PageSpace);
 };
 
 }  // namespace dart
 
 #endif  // VM_PAGES_H_