Web MIDI: allow to show an infobar for permission requests from local files

chrome/browser/media/chrome_midi_permission_context.cc

 // Copyright 2013 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/media/chrome_midi_permission_context.h"
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/content_settings/permission_queue_controller.h"
 #include "chrome/browser/content_settings/permission_request_id.h"
@@ skipping 35 matching lines @@
   content::WebContents* web_contents =
     tab_util::GetWebContentsByID(render_process_id, render_view_id);
 
   // The page doesn't exist any more.
   if (!web_contents)
     return;
 
   const PermissionRequestID id(render_process_id, render_view_id, bridge_id);
 
   GURL embedder = web_contents->GetURL();
-  if (!requesting_frame.is_valid() || !embedder.is_valid()) {
+  // |requesting_frame| can be empty and invalid when the frame is a local
+  // file. Here local files should be granted to show an infobar.
+  // Any user's action will not be stored to content settings data base.
+  if ((!requesting_frame.is_valid() && !requesting_frame.is_empty()) ||
+      !embedder.is_valid()) {
     LOG(WARNING) << "Attempt to use MIDI sysex from an invalid URL: "
                  << requesting_frame << "," << embedder
                  << " (Web MIDI is not supported in popups)";
     PermissionDecided(id, requesting_frame, embedder, callback, false);
     return;
   }
 
   DecidePermission(id, requesting_frame, embedder, callback);
 }
 
@@ skipping 73 matching lines @@
   return permission_queue_controller_.get();
 }
 
 void ChromeMIDIPermissionContext::CancelPendingInfoBarRequest(
     const PermissionRequestID& id) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   if (shutting_down_)
     return;
   GetQueueController()->CancelInfoBarRequest(id);
 }