Use DownloadManager to download non-html res when download icon pressed

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 "components/offline_pages/core/client_namespace_constants.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::ScheduleDownload(
       web_contents, offline_pages::kDownloadNamespace, url,
       offline_pages::OfflinePageUtils::DownloadUIActionFlags::ALL);
 }
 }  // 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)) {
+  if (offline_pages::OfflinePageUtils::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