Implement Dump-on-DCHECK (via a new LogSeverity).

base/allocator/partition_allocator/partition_alloc.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_H
 #define BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_H
 
 // DESCRIPTION
 // partitionAlloc() / PartitionAllocGeneric() and PartitionFree() /
 // PartitionFreeGeneric() are approximately analagous to malloc() and free().
@@ skipping 489 matching lines @@
   uintptr_t masked = ByteSwapUintPtrT(reinterpret_cast<uintptr_t>(ptr));
 #endif
   return reinterpret_cast<PartitionFreelistEntry*>(masked);
 }
 
 ALWAYS_INLINE size_t PartitionCookieSizeAdjustAdd(size_t size) {
 #if DCHECK_IS_ON()
   // Add space for cookies, checking for integer overflow. TODO(palmer):
   // Investigate the performance and code size implications of using
   // CheckedNumeric throughout PA.
-  DCHECK(size + (2 * kCookieSize) > size);
+  CHECK(size + (2 * kCookieSize) > size);

[Nico, 2017/01/17 13:03:41]

You lost me in the first file already. Why do we have a CHECK() in a
DCHECK_IS_ON #if? Even if it's intentional for some reason, that looks like a
bug.

   size += 2 * kCookieSize;
 #endif
   return size;
 }
 
 ALWAYS_INLINE size_t PartitionCookieSizeAdjustSubtract(size_t size) {
 #if DCHECK_IS_ON()
   // Remove space for cookies.
   DCHECK(size >= 2 * kCookieSize);
   size -= 2 * kCookieSize;
@@ skipping 375 matching lines @@
   void init() { PartitionAllocGenericInit(&partition_root_); }
   ALWAYS_INLINE PartitionRootGeneric* root() { return &partition_root_; }
 
  private:
   PartitionRootGeneric partition_root_;
 };
 
 }  // namespace base
 
 #endif  // BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_H