Implement committed physical memory stats for Linux.

src/heap.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 469 matching lines @@
   // Returns the capacity of the heap in bytes w/o growing. Heap grows when
   // more spaces are needed until it reaches the limit.
   intptr_t Capacity();
 
   // Returns the amount of memory currently committed for the heap.
   intptr_t CommittedMemory();
 
   // Returns the amount of executable memory currently committed for the heap.
   intptr_t CommittedMemoryExecutable();
 
+  // Returns the amount of phyical memory currently committed for the heap.
+  size_t CommittedPhysicalMemory();
+
   // Returns the available bytes in space w/o growing.
   // Heap doesn't guarantee that it can allocate an object that requires
   // all available bytes. Check MaxHeapObjectSize() instead.
   intptr_t Available();
 
   // Returns of size of all objects residing in the heap.
   intptr_t SizeOfObjects();
 
   // Return the starting address and a mask for the new space.  And-masking an
   // address with the mask will result in the start address of the new space
@@ skipping 2294 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_