Prevent data read errors from crashing the browser.

chrome/browser/renderer_host/download_throttling_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/download_throttling_resource_handler.h"
 
 #include "chrome/browser/renderer_host/download_resource_handler.h"
 #include "net/base/io_buffer.h"
 
 DownloadThrottlingResourceHandler::DownloadThrottlingResourceHandler(
@@ skipping 86 matching lines @@
   return true;
 }
 
 bool DownloadThrottlingResourceHandler::OnResponseCompleted(
     int request_id,
     const URLRequestStatus& status,
     const std::string& security_info) {
   if (download_handler_.get())
     return download_handler_->OnResponseCompleted(request_id, status,
                                                   security_info);
+
+  // For a download, if ResourceDispatcher::Read() fails,
+  // ResourceDispatcher::OnresponseStarted() will call
+  // OnResponseCompleted(), and we will end up here with an error
+  // status.
+  if (!status.is_success())
+    return false;
   NOTREACHED();
   return true;
 }
 
 void DownloadThrottlingResourceHandler::CancelDownload() {
   host_->CancelRequest(render_process_host_id_, request_id_, false);
 }
 
 void DownloadThrottlingResourceHandler::ContinueDownload() {
   DCHECK(!download_handler_.get());
@@ skipping 22 matching lines @@
   int buf_size;
   if (download_handler_->OnWillRead(request_id_, &buffer, &buf_size,
                                     tmp_buffer_length_)) {
     CHECK(buf_size >= tmp_buffer_length_);
     memcpy(buffer->data(), tmp_buffer_->data(), tmp_buffer_length_);
     download_handler_->OnReadCompleted(request_id_, &tmp_buffer_length_);
   }
   tmp_buffer_length_ = 0;
   tmp_buffer_ = NULL;
 }