Implement ManifestFetcher, helper to fetch Web Manifests.

content/renderer/fetchers/manifest_fetcher.cc

+// Copyright 2014 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/renderer/fetchers/manifest_fetcher.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "content/public/renderer/resource_fetcher.h"
+#include "third_party/WebKit/public/platform/WebURLRequest.h"
+#include "third_party/WebKit/public/web/WebFrame.h"
+
+namespace content {
+
+ManifestFetcher::ManifestFetcher(const GURL& url)
+    : completed_(false) {
+  fetcher_.reset(ResourceFetcher::Create(url));
+}
+
+ManifestFetcher::~ManifestFetcher() {
+  if (!completed_)
+    Cancel();
+}
+
+void ManifestFetcher::Start(blink::WebFrame* frame, const Callback& callback) {
+  callback_ = callback;
+  fetcher_->Start(frame,
+                  blink::WebURLRequest::RequestContextManifest,
+                  blink::WebURLRequest::FrameTypeNone,
+                  ResourceFetcher::FRAME_ASSOCIATED_LOADER,
+                  base::Bind(&ManifestFetcher::OnLoadComplete,
+                             base::Unretained(this)));
+}
+
+void ManifestFetcher::Cancel() {
+  DCHECK(!completed_);
+  fetcher_->Cancel();
+}
+
+void ManifestFetcher::OnLoadComplete(const blink::WebURLResponse& response,
+                                     const std::string& data) {
+  DCHECK(!completed_);
+  completed_ = true;
+
+  Callback callback = callback_;
+  callback.Run(response, data);
+}
+
+} // namespace content