Implement chrome.downloads.onDeterminingFilename()

chrome/browser/extensions/api/web_request/web_request_api.cc

 // Copyright (c) 2012 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/extensions/api/web_request/web_request_api.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 351 matching lines @@
       GURL(), extensions::EventRouter::USER_GESTURE_UNKNOWN,
       extensions::EventFilteringInfo()));
   event_router->DispatchEventToExtension(extension_id, event.Pass());
 }
 
 }  // namespace
 
 // Represents a single unique listener to an event, along with whatever filter
 // parameters and extra_info_spec were specified at the time the listener was
 // added.
+// NOTE(benjhayden) New APIs should not use this sub_event_name trick! It does
+// not play well with event pages. See downloads.onDeterminingFilename and
+// ExtensionDownloadsEventRouter for an alternative approach.
 struct ExtensionWebRequestEventRouter::EventListener {
   std::string extension_id;
   std::string extension_name;
   std::string sub_event_name;
   RequestFilter filter;
   int extra_info_spec;
   int target_process_id;
   int target_route_id;
   base::WeakPtr<IPC::Sender> ipc_sender;
   mutable std::set<uint64> blocked_requests;
@@ skipping 1649 matching lines @@
       } else if ((*it)->name().find("AdBlock") != std::string::npos) {
         adblock = true;
       } else {
         other = true;
       }
     }
   }
 
   host->Send(new ExtensionMsg_UsingWebRequestAPI(adblock, adblock_plus, other));
 }