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/logging.h"
+#include "third_party/WebKit/public/platform/WebURLError.h"
+#include "third_party/WebKit/public/platform/WebURLLoader.h"
+#include "third_party/WebKit/public/platform/WebURLRequest.h"
+#include "third_party/WebKit/public/web/WebDocument.h"
+#include "third_party/WebKit/public/web/WebFrame.h"
+
+namespace content {
+
+ManifestFetcher::ManifestFetcher(const GURL& url)
+    : request_(url) {
+}
+
+ManifestFetcher::~ManifestFetcher() {
+  if (!completed() && loader_)
+    Cancel();
+}
+
+void ManifestFetcher::Start(blink::WebFrame* frame, const Callback& callback) {
+  DCHECK(!loader_);
+  DCHECK(!request_.isNull());
+  DCHECK(callback_.is_null());
+  DCHECK(!completed());
+  if (!request_.httpBody().isNull())
+    DCHECK_NE("GET", request_.httpMethod().utf8()) << "GETs can't have bodies.";
+
+  callback_ = callback;
+
+  request_.setRequestContext(blink::WebURLRequest::RequestContextManifest);

[Mike West, 2014/09/10 14:00:12]

Perhaps this could be deduped by adding ::Start method to the superclass, and
passing through the call here along with the context, type, and loader?

+  request_.setFrameType(blink::WebURLRequest::FrameTypeNone);
+  request_.setFirstPartyForCookies(frame->document().firstPartyForCookies());
+  frame->dispatchWillSendRequest(request_);
+  loader_.reset(frame->createAssociatedURLLoader());
+  loader_->loadAsynchronously(request_, this);
+
+  request_.reset();
+}
+
+void ManifestFetcher::Cancel() {
+  loader_->cancel();
+  WebURLLoaderClientImpl::Cancel();
+}
+
+void ManifestFetcher::OnLoadComplete() {
+  if (callback_.is_null())
+    return;
+
+  Callback callback = callback_;
+  callback.Run(status() == LOAD_FAILED ? blink::WebURLResponse() : response(),
+               status() == LOAD_FAILED ? std::string() : data());
+}
+
+} // namespace content