Update the PartitionAlloc documentation.

third_party/WebKit/Source/platform/wtf/allocator/Partitions.h

 /*
  * Copyright (C) 2013 Google Inc. 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
@@ skipping 112 matching lines @@
   static void FastFree(void* p) {
     PartitionFreeGeneric(Partitions::FastMallocPartition(), p);
   }
 
   static void HandleOutOfMemory();
 
  private:
   static base::subtle::SpinLock initialization_lock_;
   static bool initialized_;
 
-  // We have the following four partitions.
-  //   - LayoutObject partition: A partition to allocate LayoutObjects.
-  //     We prepare a dedicated partition for LayoutObjects because they
-  //     are likely to be a source of use-after-frees. Another reason
-  //     is for performance: As LayoutObjects are guaranteed to only be used
-  //     by the main thread, we can bypass acquiring a lock. Also we can
-  //     improve memory locality by putting LayoutObjects together.
-  //   - ArrayBuffer partition: A partition to allocate array buffers.
-  //   - Buffer partition: A partition to allocate other buffers that have
-  //     a strong risk where the length and/or the contents are exploited from
-  //     user scripts. Vectors, HashTables and Strings are allocated in the
-  //      buffer partition.
-  //   - Fast malloc partition: A partition to allocate all other objects.
+  // See Allocator.md for a description of these partitions.
   static base::PartitionAllocatorGeneric fast_malloc_allocator_;
   static base::PartitionAllocatorGeneric array_buffer_allocator_;
   static base::PartitionAllocatorGeneric buffer_allocator_;
   static base::SizeSpecificPartitionAllocator<1024> layout_allocator_;
   static ReportPartitionAllocSizeFunction report_size_function_;
 };
 
 using base::kGenericMaxDirectMapped;
 using base::kPageAllocationGranularity;
 using base::kPageAllocationGranularityBaseMask;
@@ skipping 15 matching lines @@
 using base::PageAccessible;
 using base::PageInaccessible;
 using base::PartitionStatsDumper;
 using base::PartitionMemoryStats;
 using base::PartitionBucketMemoryStats;
 using base::PartitionAllocHooks;
 
 }  // namespace WTF
 
 #endif  // Partitions_h