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

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

Index: chrome/browser/android/offline_pages/downloads/resource_throttle.cc
diff --git a/chrome/browser/android/offline_pages/downloads/resource_throttle.cc b/chrome/browser/android/offline_pages/downloads/resource_throttle.cc
index ee6aec8c702f1dfd0ea6a899ba3b019f13d9023f..dcdea5c7bfed7824e91c0162eb25928906cb1802 100644
--- a/chrome/browser/android/offline_pages/downloads/resource_throttle.cc
+++ b/chrome/browser/android/offline_pages/downloads/resource_throttle.cc
@@ -10,18 +10,8 @@
 #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 {
-// Check if the url and mime type of a download resource should trigger handoff
-// to OfflinePages backend for full page load and snapshot.
-bool CanDownloadAsOfflinePage(
-    const GURL& url, const std::string& contents_mime_type) {
-  return url.SchemeIsHTTPOrHTTPS() &&
-      (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) {
@@ -51,8 +41,8 @@ void ResourceThrottle::WillProcessResponse(bool* defer) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
   std::string mime_type;
   request_->GetMimeType(&mime_type);
-
-  if (CanDownloadAsOfflinePage(request_->url(), mime_type)) {
+  if (offline_pages::OfflinePageUtils::CanDownloadAsOfflinePage(request_->url(),
+                                                                mime_type)) {
     const content::ResourceRequestInfo* info =
         content::ResourceRequestInfo::ForRequest(request_);
     if (!info)