[Android Downloads] Long-press menu item "Download Link" should delegate job to OfflinePages backen…

chrome/browser/android/offline_pages/downloads/resource_throttle.cc

+// Copyright 2016 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 "chrome/browser/android/offline_pages/downloads/resource_throttle.h"
+
+#include "base/logging.h"
+#include "chrome/browser/android/offline_pages/offline_page_utils.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/resource_request_info.h"
+#include "content/public/browser/web_contents.h"
+#include "net/base/mime_util.h"
+
+namespace {
+// Mime type of download resource that should trigger handoff to OfflinePages
+// backend for full page load and snapshot.
+bool CanDownloadAsOfflinePage(const std::string& contents_mime_type) {
+  return net::MatchesMimeType(contents_mime_type, "text/html") ||
+         net::MatchesMimeType(contents_mime_type, "application/xhtml+xml");
+}
+
+void WillStartOfflineRequestOnUIThread(
+    const GURL& url,
+    const content::ResourceRequestInfo::WebContentsGetter& contents_getter) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  content::WebContents* web_contents = contents_getter.Run();
+  if (!web_contents)
+    return;
+  offline_pages::OfflinePageUtils::StartOfflinePageDownload(
+      web_contents->GetBrowserContext(), url);
+}
+}  // namespace
+
+namespace offline_pages {
+namespace downloads {
+
+ResourceThrottle::ResourceThrottle(const net::URLRequest* request)
+    : request_(request) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+}
+
+ResourceThrottle::~ResourceThrottle() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+}
+
+void ResourceThrottle::WillProcessResponse(bool* defer) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+  std::string mime_type;
+  request_->GetMimeType(&mime_type);
+  if (CanDownloadAsOfflinePage(mime_type)) {
+    const content::ResourceRequestInfo* info =
+        content::ResourceRequestInfo::ForRequest(request_);
+    if (!info)
+      return;
+    content::BrowserThread::PostTask(
+        content::BrowserThread::UI, FROM_HERE,
+        base::Bind(&WillStartOfflineRequestOnUIThread, request_->url(),
+                   info->GetWebContentsGetterForRequest()));
+    Cancel();
+  }
+}
+
+const char* ResourceThrottle::GetNameForLogging() const {
+  return "offline_pages::downloads::ResourceThrottle";
+}
+
+}  // namespace downloads
+}  // namespace offline_pages