Update from https://crrev.com/315085

net/disk_cache/blockfile/block_files.cc

 // Copyright (c) 2012 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 "net/disk_cache/blockfile/block_files.h"
 
 #include "base/atomicops.h"
 #include "base/files/file_path.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ skipping 638 matching lines @@
 
 // Note that we expect to be called outside of a FileLock... however, we cannot
 // DCHECK on header->updating because we may be fixing a crash.
 bool BlockFiles::FixBlockFileHeader(MappedFile* file) {
   ScopedFlush flush(file);
   BlockHeader file_header(file);
   int file_size = static_cast<int>(file->GetLength());
   if (file_size < file_header.Size())
     return false;  // file_size > 2GB is also an error.
 
-  const int kMinBlockSize = 36;
-  const int kMaxBlockSize = 4096;
+  const int kMinHeaderBlockSize = 36;
+  const int kMaxHeaderBlockSize = 4096;
   BlockFileHeader* header = file_header.Header();
-  if (header->entry_size < kMinBlockSize ||
-      header->entry_size > kMaxBlockSize || header->num_entries < 0)
+  if (header->entry_size < kMinHeaderBlockSize ||
+      header->entry_size > kMaxHeaderBlockSize || header->num_entries < 0)
     return false;
 
   // Make sure that we survive crashes.
   header->updating = 1;
   int expected = header->entry_size * header->max_entries + file_header.Size();
   if (file_size != expected) {
     int max_expected = header->entry_size * kMaxBlocks + file_header.Size();
     if (file_size < expected || header->empty[3] || file_size > max_expected) {
       NOTREACHED();
       LOG(ERROR) << "Unexpected file size";
@@ skipping 48 matching lines @@
 }
 
 base::FilePath BlockFiles::Name(int index) {
   // The file format allows for 256 files.
   DCHECK(index < 256 && index >= 0);
   std::string tmp = base::StringPrintf("%s%d", kBlockName, index);
   return path_.AppendASCII(tmp);
 }
 
 }  // namespace disk_cache