Fix silent truncations when extracting values from CheckedNumeric

components/nacl/browser/pnacl_host.cc

 // Copyright 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.
 
 #include "components/nacl/browser/pnacl_host.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 400 matching lines @@
   // TODO(eroman): Maximum size should be changed to size_t once that is
   // what IOBuffer requires. crbug.com/488553. Also I don't think the
   // max size should be inclusive here...
   int64_t file_size = file->GetLength();
   if (file_size < 0 || file_size > std::numeric_limits<int>::max()) {
     PLOG(ERROR) << "Get file length failed " << file_size;
     return buffer;
   }
 
   buffer = new net::DrainableIOBuffer(
-      new net::IOBuffer(base::CheckedNumeric<size_t>(file_size).ValueOrDie()),
-      base::CheckedNumeric<size_t>(file_size).ValueOrDie());
+      new net::IOBuffer(base::checked_cast<size_t>(file_size)),
+      base::checked_cast<size_t>(file_size));
   if (file->Read(0, buffer->data(), buffer->size()) != file_size) {
     PLOG(ERROR) << "CopyFileToBuffer file read failed";
     buffer = nullptr;
   }
   return buffer;
 }
 
 // Called by the renderer in the miss path to report a finished translation
 void PnaclHost::TranslationFinished(int render_process_id,
                                     int pp_instance,
@@ skipping 226 matching lines @@
   DCHECK(pending_backend_operations_ >= 0);
   if (pending_translations_.empty() &&
       pending_backend_operations_ <= 0 &&
       cache_state_ == CacheReady) {
     cache_state_ = CacheUninitialized;
     disk_cache_.reset();
   }
 }
 
 }  // namespace pnacl