Adding V8 api to get memory statistics of spaces in V8::Heap.

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
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   size_t total_heap_size_executable_;
   size_t total_physical_size_;
   size_t used_heap_size_;
   size_t heap_size_limit_;
 
   friend class V8;
   friend class Isolate;
 };
 
 
+class HeapSpaceStatistics {
+ public:
+  HeapSpaceStatistics();
+  const char* space_name() { return space_name_; }
+  size_t space_size() { return space_size_; }
+  size_t space_used_size() { return space_used_size_; }
+  size_t space_available_size() { return space_available_size_; }
+  size_t physical_space_size() { return physical_space_size_; }
+
+ private:
+  const char* space_name_;
+  size_t space_size_;
+  size_t space_used_size_;
+  size_t space_available_size_;
+  size_t physical_space_size_;
+
+  friend class Isolate;
+};
+
+
 class RetainedObjectInfo;
 
 
 /**
  * FunctionEntryHook is the type of the profile entry hook called at entry to
  * any generated function when function-level profiling is enabled.
  *
  * \param function the address of the function that's being entered.
  * \param return_addr_location points to a location on stack where the machine
  *    return address resides. This can be used to identify the caller of
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    * are in the range of 0 - GetNumberOfDataSlots() - 1.
    */
   V8_INLINE static uint32_t GetNumberOfDataSlots();
 
   /**
    * Get statistics about the heap memory usage.
    */
   void GetHeapStatistics(HeapStatistics* heap_statistics);
 
   /**
+   * Returns the number of spaces in the heap.
+   */
+  size_t NumberOfHeapSpaces();
+
+  /**
+   * Get the memory usage of a space in the heap.
+   *
+   * \param space_statistics The HeapSpaceStatistics object to fill in
+   *   statistics.
+   * \param index The index of the space to get statistics from, which ranges
+   *   from 0 to NumberOfHeapSpaces() - 1.
+   * \returns true on success.
+   */
+  bool GetHeapSpaceStatistics(HeapSpaceStatistics* space_statistics,
+                              size_t index);
+
+  /**
    * Get a call stack sample from the isolate.
    * \param state Execution state.
    * \param frames Caller allocated buffer to store stack frames.
    * \param frames_limit Maximum number of frames to capture. The buffer must
    *                     be large enough to hold the number of frames.
    * \param sample_info The sample info is filled up by the function
    *                    provides number of actual captured stack frames and
    *                    the current VM state.
    * \note GetStackSample should only be called when the JS thread is paused or
    *       interrupted. Otherwise the behavior is undefined.
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  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_