Upstream most of the iOS WebUI support in ios/web/

ios/web/webui/url_fetcher_block_adapter.mm

+// Copyright 2015 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 "ios/web/webui/url_fetcher_block_adapter.h"
+
+#include "base/logging.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_request_context_getter.h"
+
+namespace web {
+
+URLFetcherBlockAdapter::URLFetcherBlockAdapter(
+    const GURL& url,
+    net::URLRequestContextGetter* request_context,
+    web::URLFetcherBlockAdapterCompletion completion_handler)
+    : url_(url),
+      request_context_(request_context),
+      completion_handler_([completion_handler copy]) {
+}
+
+URLFetcherBlockAdapter::~URLFetcherBlockAdapter() {
+}
+
+void URLFetcherBlockAdapter::Start() {
+  fetcher_.reset(net::URLFetcher::Create(url_, net::URLFetcher::GET, this));
+  fetcher_->SetRequestContext(request_context_);
+  fetcher_->Start();
+}
+
+void URLFetcherBlockAdapter::OnURLFetchComplete(const net::URLFetcher* source) {
+  std::string response;
+  if (!source->GetResponseAsString(&response)) {
+    DLOG(WARNING) << "String for resource URL not found" << source->GetURL();
+  }
+  NSData* data =
+      [NSData dataWithBytes:response.c_str() length:response.length()];
+  completion_handler_.get()(data, this);
+}
+
+}  // namespace web