Fix silent truncations when extracting values from CheckedNumeric

content/browser/appcache/appcache_internals_ui.cc

 // Copyright 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 "content/browser/appcache/appcache_internals_ui.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 269 matching lines @@
     return;
   if (!appcache_service_)
     return;
   ResponseEnquiry response_enquiry = response_enquiries_.front();
   response_enquiries_.pop_front();
   if (response) {
     scoped_refptr<AppCacheResponseInfo> response_info = response;
     const int64_t kLimit = 100 * 1000;
     int64_t amount_to_read =
         std::min(kLimit, response_info->response_data_size());
-    scoped_refptr<net::IOBuffer> response_data(new net::IOBuffer(
-        base::CheckedNumeric<size_t>(amount_to_read).ValueOrDie()));
+    scoped_refptr<net::IOBuffer> response_data(
+        new net::IOBuffer(base::checked_cast<size_t>(amount_to_read)));
     std::unique_ptr<AppCacheResponseReader> reader(
         appcache_service_->storage()->CreateResponseReader(
             GURL(response_enquiry.manifest_url), response_enquiry.response_id));
 
     reader->ReadData(
         response_data.get(), amount_to_read,
         base::Bind(&Proxy::OnResponseDataReadComplete, this, response_enquiry,
                    response_info, base::Passed(&reader), response_data));
   } else {
     OnResponseDataReadComplete(response_enquiry, nullptr, nullptr, nullptr, -1);
@@ skipping 201 matching lines @@
     const base::FilePath& partition_path) {
   for (const scoped_refptr<Proxy>& proxy : appcache_proxies_) {
     if (proxy->partition_path_ == partition_path)
       return proxy.get();
   }
   NOTREACHED();
   return nullptr;
 }
 
 }  // namespace content