Add methods to enable configuration of ResourceConstraints based on limits derived at runtime.

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 287 matching lines @@
   static void SignalCodeMovingGC();
 
   // The return value indicates the CPU features we are sure of because of the
   // OS.  For example MacOSX doesn't run on any x86 CPUs that don't have SSE2
   // instructions.
   // This is a little messy because the interpretation is subject to the cross
   // of the CPU and the OS.  The bits in the answer correspond to the bit
   // positions indicated by the members of the CpuFeature enum from globals.h
   static uint64_t CpuFeaturesImpliedByPlatform();
 
+  // The total amount of physical memory available on the current system.
+  static uint64_t TotalPhysicalMemory();
+
   // Maximum size of the virtual memory.  0 means there is no artificial
   // limit.
   static intptr_t MaxVirtualMemory();
 
   // Returns the double constant NAN
   static double nan_value();
 
   // Support runtime detection of whether the hard float option of the
   // EABI is used.
   static bool ArmUsingHardFloat();
@@ skipping 274 matching lines @@
   char name_[kMaxThreadNameLength];
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_