1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "content/browser/webui/url_data_source_impl.h"
6
7#include "base/bind.h"
8#include "base/memory/ref_counted_memory.h"
9#include "base/strings/string_util.h"
10#include "content/browser/webui/url_data_manager_backend.h"
11#include "content/public/browser/browser_thread.h"
12#include "content/public/browser/url_data_source.h"
13
14namespace content {
15
16URLDataSourceImpl::URLDataSourceImpl(const std::string& source_name,
17                                     URLDataSource* source)
18    : source_name_(source_name),
19      backend_(NULL),
20      source_(source) {
21}
22
23URLDataSourceImpl::~URLDataSourceImpl() {
24}
25
26void URLDataSourceImpl::SendResponse(
27    int request_id,
28    base::RefCountedMemory* bytes) {
29  // Take a ref-pointer on entry so byte->Release() will always get called.
30  scoped_refptr<base::RefCountedMemory> bytes_ptr(bytes);
31  if (URLDataManager::IsScheduledForDeletion(this)) {
32    // We're scheduled for deletion. Servicing the request would result in
33    // this->AddRef being invoked, even though the ref count is 0 and 'this' is
34    // about to be deleted. If the AddRef were allowed through, when 'this' is
35    // released it would be deleted again.
36    //
37    // This scenario occurs with DataSources that make history requests. Such
38    // DataSources do a history query in |StartDataRequest| and the request is
39    // live until the object is deleted (history requests don't up the ref
40    // count). This means it's entirely possible for the DataSource to invoke
41    // |SendResponse| between the time when there are no more refs and the time
42    // when the object is deleted.
43    return;
44  }
45  BrowserThread::PostTask(
46      BrowserThread::IO, FROM_HERE,
47      base::Bind(&URLDataSourceImpl::SendResponseOnIOThread, this, request_id,
48                 bytes_ptr));
49}
50
51void URLDataSourceImpl::SendResponseOnIOThread(
52    int request_id,
53    scoped_refptr<base::RefCountedMemory> bytes) {
54  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
55  if (backend_)
56    backend_->DataAvailable(request_id, bytes.get());
57}
58
59}  // namespace content
60