Cancel MIDI permission request infobar on MIDIAccess stop.

content/renderer/media/midi_dispatcher.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 "content/renderer/media/midi_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "content/common/media/midi_messages.h"
 #include "content/renderer/render_view_impl.h"
@@ skipping 16 matching lines @@
   IPC_BEGIN_MESSAGE_MAP(MIDIDispatcher, message)
     IPC_MESSAGE_HANDLER(MIDIMsg_SysExPermissionApproved,
                         OnSysExPermissionApproved)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void MIDIDispatcher::requestSysExPermission(
       const WebMIDIPermissionRequest& request) {
-  int client_id = requests_.Add(new WebMIDIPermissionRequest(request));
+  int bridge_id = requests_.Add(new WebMIDIPermissionRequest(request));
   WebSecurityOrigin security_origin = request.securityOrigin();
   std::string origin = security_origin.toString().utf8();
   GURL url(origin);
-  Send(new MIDIHostMsg_RequestSysExPermission(routing_id(), client_id, url));
+  Send(new MIDIHostMsg_RequestSysExPermission(routing_id(), bridge_id, url));
 }
 
 void MIDIDispatcher::cancelSysExPermissionRequest(
     const WebMIDIPermissionRequest& request) {

[Kibeom Kim (inactive), 2013/10/23 23:37:31]

ddorwin@ or scherkus@ or xhwang@:
This is triggered by ExecutionContext::stopActiveDOMObjects(). In case of EME,
where should I request infobar cancellation?

[ddorwin, 2013/10/23 23:52:40]

Can you provide more details on the exact path?

The currently shipping EME APIs go through HTMLMediaElement, which is also an
ActiveDOMObject with a stop() method [1]. stop() calls userCancelledLoad(),
which destroys the WebMediaPlayerImpl/WebMediaPlayerAndroid (Chromium side of
things). Should it go in the destructor of those classes? However, you could
have multiple <video> in a page, and destroying one shouldn't necessarily cancel
the infobar, so you'd need to know which one it was or somehow hook up to the
main stopActiveDOMObjects().

(The newer unprefixed APIs have a different path that we'll have to address
later.)

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

[Kibeom Kim (inactive), 2013/10/24 00:00:05]

This is the call stack for MIDI.

Started by one of these four:
- WebCore::ExecutionContext::stopActiveDOMObjects() ->
WebCore::ContextLifecycleNotifier::notifyStoppingActiveDOMObjects()
- WebCore::MIDIAccess::~MIDIAccess()
- WebCore::MIDIAccessPromise::~MIDIAccessPromise()
- WebCore::MIDIPort::~MIDIPort()

Then goes:
WebCore::MIDIAccess::stop()
WebCore::MIDIController::cancelSysExPermissionRequest(MIDIAccess *)
WebKit::MIDIClientProxy::cancelSysExPermissionRequest(MIDIAccess *)
content::MIDIDispatcher::cancelSysExPermissionRequest(const
WebMIDIPermissionRequest &)

   for (IDMap<WebMIDIPermissionRequest>::iterator it(&requests_);
        !it.IsAtEnd();
        it.Advance()) {
     WebMIDIPermissionRequest* value = it.GetCurrentValue();
-    if (!value->equals(request))
-      continue;
-    requests_.Remove(it.GetCurrentKey());
+    if (value->equals(request)) {
+      requests_.Remove(it.GetCurrentKey());
+      string16 origin = request.securityOrigin().toString();
+      Send(new MIDIHostMsg_CancelSysExPermissionRequest(
+          routing_id(), it.GetCurrentKey(), GURL(origin)));
+      break;
+    }
   }
 }
 
-void MIDIDispatcher::OnSysExPermissionApproved(int client_id, bool is_allowed) {
+void MIDIDispatcher::OnSysExPermissionApproved(int bridge_id, bool is_allowed) {
   // |request| can be NULL when the request is canceled.
-  WebMIDIPermissionRequest* request = requests_.Lookup(client_id);
+  WebMIDIPermissionRequest* request = requests_.Lookup(bridge_id);
   if (!request)
     return;
   request->setIsAllowed(is_allowed);
-  requests_.Remove(client_id);
+  requests_.Remove(bridge_id);
 }
 
 }  // namespace content