Expose the virtual memory limit to blink

base/sys_info.h

Index: base/sys_info.h
diff --git a/base/sys_info.h b/base/sys_info.h
index aa40cadfbc93791dc57b9513554bea33d4b05c3b..7ce4e659f28b989e1151dddc3cf431923768539e 100644
--- a/base/sys_info.h
+++ b/base/sys_info.h
@@ -28,11 +28,22 @@ class BASE_EXPORT SysInfo {
   // machine.
   static int64 AmountOfAvailablePhysicalMemory();
 
+  // Return the number of bytes of virtual memory of this process. A return
+  // value of zero means that there is no limit on the available virtual
+  // memory.
+  static int64 AmountOfVirtualMemory();
+
   // Return the number of megabytes of physical memory on the current machine.
   static int AmountOfPhysicalMemoryMB() {
     return static_cast<int>(AmountOfPhysicalMemory() / 1024 / 1024);
   }
 
+  // Return the number of megabytes of available virtual memory, or zero if it
+  // is unlimited.
+  static int AmountOfVirtualMemoryMB() {
+    return static_cast<int>(AmountOfVirtualMemory() / 1024 / 1024);
+  }
+
   // Return the available disk space in bytes on the volume containing |path|,
   // or -1 on failure.
   static int64 AmountOfFreeDiskSpace(const FilePath& path);