Do not cache an IOBuffer in AsyncResourceHandler if data_ is NULL.

chrome/browser/renderer_host/async_resource_handler.cc

 // Copyright (c) 2006-2008 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 "chrome/browser/renderer_host/async_resource_handler.h"
 
 #include "base/logging.h"
 #include "base/process.h"
 #include "base/shared_memory.h"
 #include "chrome/common/render_messages.h"
@@ skipping 123 matching lines @@
     const std::string& security_info) {
   receiver_->Send(new ViewMsg_Resource_RequestComplete(routing_id_,
                                                        request_id,
                                                        status,
                                                        security_info));
 
   // If we still have a read buffer, then see about caching it for later...
   if (g_spare_read_buffer) {
     read_buffer_ = NULL;
   } else if (read_buffer_.get()) {
+    // TODO(willchan): Remove after debugging bug 16371.
+    CHECK(read_buffer_->data());
     read_buffer_.swap(&g_spare_read_buffer);
   }
   return true;
 }
 
 // static
 void AsyncResourceHandler::GlobalCleanup() {
   if (g_spare_read_buffer) {
     // Avoid the CHECK in SharedIOBuffer::~SharedIOBuffer().
     SharedIOBuffer* tmp = g_spare_read_buffer;
     g_spare_read_buffer = NULL;
     tmp->Release();
   }
 }