Implement ManifestFetcher, helper to fetch Web Manifests.

content/renderer/fetchers/manifest_fetcher.h

+// 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.
+
+#ifndef CONTENT_RENDERER_FETCHERS_MANIFEST_FETCHER_H_
+#define CONTENT_RENDERER_FETCHERS_MANIFEST_FETCHER_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"
+#include "third_party/WebKit/public/platform/WebURLResponse.h"
+
+class GURL;
+
+namespace blink {
+class WebFrame;
+}
+
+namespace content {
+
+class ResourceFetcher;
+
+// Helper class to download a Web Manifest. When an instance is created, the
+// caller need to call Start() and wait for the passed callback to be executed.
+// If the fetch fails, the callback will be called with two empty objects.
+class ManifestFetcher {
+ public:
+  // This will be called asynchronously after the URL has been fetched,
+  // successfully or not.  If there is a failure, response and data will both be
+  // empty.  |response| and |data| are both valid until the URLFetcher instance
+  // is destroyed.
+  typedef base::Callback<void(const blink::WebURLResponse& response,
+                              const std::string& data)> Callback;
+
+  explicit ManifestFetcher(const GURL& url);
+  virtual ~ManifestFetcher();
+
+  void Start(blink::WebFrame* frame, const Callback& callback);
+  void Cancel();
+
+ private:
+  void OnLoadComplete(const blink::WebURLResponse& response,
+                      const std::string& data);
+
+  bool completed_;
+  Callback callback_;
+  scoped_ptr<ResourceFetcher> fetcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestFetcher);
+};
+
+} // namespace content
+
+#endif // CONTENT_RENDERER_FETCHERS_MANIFEST_FETCHER_H_