Implement ManifestFetcher, helper to fetch Web Manifests.

content/renderer/fetchers/manifest_fetcher.h

Index: content/renderer/fetchers/manifest_fetcher.h
diff --git a/content/renderer/fetchers/manifest_fetcher.h b/content/renderer/fetchers/manifest_fetcher.h
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+++ b/content/renderer/fetchers/manifest_fetcher.h
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+// 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 "content/renderer/fetchers/web_url_loader_client_impl.h"
+#include "third_party/WebKit/public/platform/WebURLRequest.h"
+#include "third_party/WebKit/public/platform/WebURLResponse.h"
+
+class GURL;
+
+namespace blink {
+class WebFrame;
+class WebURLLoader;
+struct WebURLError;
+}
+
+namespace content {
+
+// 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.
+//
+// This class is not using ResourceFetcher because ResourceFetcherImpl is using
+// Platform::createURLLoader() instead of createAssociatedURLLoader(). The
+// former is too permissive with regards to CORS and mixed content.
+class ManifestFetcher : public WebURLLoaderClientImpl {
+ 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);
+  virtual void Cancel() OVERRIDE;
+
+ private:
+  // WebURLLoaderClientImpl methods.
+  virtual void OnLoadComplete() OVERRIDE;
+
+  scoped_ptr<blink::WebURLLoader> loader_;
+
+  // Request to send.  Released once Start() is called.
+  blink::WebURLRequest request_;
+
+  // Callback when we're done.
+  Callback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestFetcher);
+};
+
+} // namespace content
+
+#endif // CONTENT_RENDERER_FETCHERS_MANIFEST_FETCHER_H_