Introduce first approximation of constructor heap profile for JS objects.

src/spaces.h

Index: src/spaces.h
diff --git a/src/spaces.h b/src/spaces.h
index 94f7a914e3b624936816070659bfc04d253601b6..9841a5fddfbab1d00e389537c0f320efa7069d82 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -931,34 +931,41 @@ class PagedSpace : public Space {
 
 
 #if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
-// HistogramInfo class for recording a single "bar" of a histogram.  This
-// class is used for collecting statistics to print to stdout (when compiled
-// with DEBUG) or to the log file (when compiled with
-// ENABLE_LOGGING_AND_PROFILING).
-class HistogramInfo BASE_EMBEDDED {
+class NumberAndSizeInfo BASE_EMBEDDED {
  public:
-  HistogramInfo() : number_(0), bytes_(0) {}
+  NumberAndSizeInfo() : number_(0), bytes_(0) {}
 
-  const char* name() { return name_; }
-  void set_name(const char* name) { name_ = name; }
-
-  int number() { return number_; }
+  int number() const { return number_; }
   void increment_number(int num) { number_ += num; }
 
-  int bytes() { return bytes_; }
+  int bytes() const { return bytes_; }
   void increment_bytes(int size) { bytes_ += size; }
 
-  // Clear the number of objects and size fields, but not the name.
   void clear() {
     number_ = 0;
     bytes_ = 0;
   }
 
  private:
-  const char* name_;
   int number_;
   int bytes_;
 };
+
+
+// HistogramInfo class for recording a single "bar" of a histogram.  This
+// class is used for collecting statistics to print to stdout (when compiled
+// with DEBUG) or to the log file (when compiled with
+// ENABLE_LOGGING_AND_PROFILING).
+class HistogramInfo: public NumberAndSizeInfo {
+ public:
+  HistogramInfo() : NumberAndSizeInfo() {}
+
+  const char* name() { return name_; }
+  void set_name(const char* name) { name_ = name; }
+
+ private:
+  const char* name_;
+};
 #endif