VM: Refactor allocation stats code and remove duplicate 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/lockers.h"
@@ skipping 279 matching lines @@
   }
 
   void IncrementCollections() {
     collections_++;
   }
 
   intptr_t collections() const {
     return collections_;
   }
 
-  void PrintToJSONObject(JSONObject* object);
-  void PrintHeapMapToJSONStream(Isolate* isolate, JSONStream* stream);
+  void PrintToJSONObject(JSONObject* object) const;
+  void PrintHeapMapToJSONStream(Isolate* isolate, JSONStream* stream) const;
 
   void AllocateExternal(intptr_t size);
   void FreeExternal(intptr_t size);
 
   // Bulk data allocation.
   void AcquireDataLock();
   void ReleaseDataLock();
 
   uword TryAllocateDataLocked(intptr_t size, GrowthPolicy growth_policy) {
     bool is_protected = false;
@@ skipping 18 matching lines @@
   uword TryAllocatePromoLocked(intptr_t size, GrowthPolicy growth_policy);
   // Allocates memory where every word is guaranteed to be a Smi. Calling this
   // method after the first garbage collection is inefficient in release mode
   // and illegal in debug mode.
   uword TryAllocateSmiInitializedLocked(intptr_t size,
                                         GrowthPolicy growth_policy);
 
   // Bump block allocation from generated code.
   uword* TopAddress() { return &bump_top_; }
   uword* EndAddress() { return &bump_end_; }
+  static intptr_t top_offset() { return OFFSET_OF(PageSpace, bump_top_); }
+  static intptr_t end_offset() { return OFFSET_OF(PageSpace, bump_end_); }
 
  private:
   // Ids for time and data records in Heap::GCStats.
   enum {
     // Time
     kMarkObjects = 0,
     kResetFreeLists = 1,
     kSweepPages = 2,
     kSweepLargePages = 3,
     // Data
@@ skipping 88 matching lines @@
   friend class HeapIterationScope;
   friend class PageSpaceController;
   friend class SweeperTask;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PageSpace);
 };
 
 }  // namespace dart
 
 #endif  // VM_PAGES_H_