Reduce memory usage in DelayedPersistentAllocation.

base/metrics/persistent_memory_allocator.cc

 // Copyright (c) 2015 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.
 
 #include "base/metrics/persistent_memory_allocator.h"
 
 #include <assert.h>
 #include <algorithm>
 
 #if defined(OS_WIN)
 #include "winbase.h"
 #elif defined(OS_POSIX)
 #include <sys/mman.h>
 #endif
 
 #include "base/files/memory_mapped_file.h"
 #include "base/logging.h"
 #include "base/memory/shared_memory.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/numerics/safe_conversions.h"
 #include "base/threading/thread_restrictions.h"
 
 namespace {
 
 // Limit of memory segment size. It has to fit in an unsigned 32-bit number
 // and should be a power of 2 in order to accomodate almost any page size.
 const uint32_t kSegmentMaxSize = 1 << 30;  // 1 GiB
 
 // A constant (random) value placed in the shared metadata to identify
 // an already initialized memory segment.
@@ skipping 1085 matching lines @@
 // Real constructor.
 DelayedPersistentAllocation::DelayedPersistentAllocation(
     PersistentMemoryAllocator* allocator,
     std::atomic<Reference>* ref,
     uint32_t type,
     size_t size,
     size_t offset,
     bool make_iterable)
     : allocator_(allocator),
       type_(type),
-      size_(size),
-      offset_(offset),
+      size_(checked_cast<uint32_t>(size)),
+      offset_(checked_cast<uint32_t>(offset)),
       make_iterable_(make_iterable),
       reference_(ref) {
   DCHECK(allocator_);
   DCHECK_NE(0U, type_);
   DCHECK_LT(0U, size_);
   DCHECK(reference_);
 }
 
 DelayedPersistentAllocation::~DelayedPersistentAllocation() {}
 
@@ skipping 30 matching lines @@
   if (!mem) {
     // This should never happen but be tolerant if it does as corruption from
     // the outside is something to guard against.
     NOTREACHED();
     return nullptr;
   }
   return mem + offset_;
 }
 
 }  // namespace base