Add counters to track the maximum amount of memory committed by the heap.

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 515 matching lines @@
 
   // 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 maximum amount of memory ever committed for the heap.
+  intptr_t MaximumCommittedMemory() { return maximum_committed_; }
+
+  // Updates the maximum committed memory for the heap. Should be called
+  // whenever a space grows.
+  void UpdateMaximumCommitted();
+
   // 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 1335 matching lines @@
   Isolate* isolate_;
 
   Object* roots_[kRootListLength];
 
   intptr_t code_range_size_;
   int reserved_semispace_size_;
   int max_semispace_size_;
   int initial_semispace_size_;
   intptr_t max_old_generation_size_;
   intptr_t max_executable_size_;
+  intptr_t maximum_committed_;
 
   // For keeping track of how much data has survived
   // scavenge since last new space expansion.
   int survived_since_last_expansion_;
 
   // For keeping track on when to flush RegExp code.
   int sweep_generation_;
 
   int always_allocate_scope_depth_;
   int linear_allocation_scope_depth_;
@@ skipping 1169 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_