Implement committed physical memory stats for Linux.

src/platform.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 411 matching lines @@
   static void* ReserveRegion(size_t size);
 
   static bool CommitRegion(void* base, size_t size, bool is_executable);
 
   static bool UncommitRegion(void* base, size_t size);
 
   // Must be called with a base pointer that has been returned by ReserveRegion
   // and the same size it was reserved with.
   static bool ReleaseRegion(void* base, size_t size);
 
+  // Returns the size of committed memory which is currently resident
+  // in the physical memory for the region specified with base and size
+  // arguments.
+  // On success stores the committed physical memory size at the location
+  // pointed by the last argument and returns true. Returns false on failure.
+  static bool CommittedPhysicalSizeInRegion(
+      void* base, size_t size, size_t* physical);
+
  private:
   void* address_;  // Start address of the virtual memory.
   size_t size_;  // Size of the virtual memory.
 };
 
 
 // ----------------------------------------------------------------------------
 // Thread
 //
 // Thread objects are used for creating and running threads. When the start()
@@ skipping 339 matching lines @@
   Atomic32 active_;
   PlatformData* data_;  // Platform specific data.
   int samples_taken_;  // Counts stack samples taken.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_