[Presentation API] fire onconnectionavailable and onconnect event asynchronously

third_party/WebKit/Source/modules/presentation/PresentationConnection.cpp

 // Copyright 2014 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 "modules/presentation/PresentationConnection.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMArrayBuffer.h"
 #include "core/dom/DOMArrayBufferView.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
+#include "core/dom/ExecutionContextTask.h"
 #include "core/events/Event.h"
 #include "core/events/MessageEvent.h"
 #include "core/fileapi/FileReaderLoader.h"
 #include "core/fileapi/FileReaderLoaderClient.h"
 #include "core/frame/Deprecation.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/UseCounter.h"
 #include "modules/EventTargetModules.h"
 #include "modules/presentation/Presentation.h"
 #include "modules/presentation/PresentationConnectionAvailableEvent.h"
@@ skipping 162 matching lines @@
 PresentationConnection* PresentationConnection::take(
     PresentationController* controller,
     std::unique_ptr<WebPresentationConnectionClient> client,
     PresentationRequest* request) {
   ASSERT(controller);
   ASSERT(request);
 
   PresentationConnection* connection = new PresentationConnection(
       controller->frame(), client->getId(), client->getUrl());
   controller->registerConnection(connection);
-  request->dispatchEvent(PresentationConnectionAvailableEvent::create(
-      EventTypeNames::connectionavailable, connection));
-
+  request->getExecutionContext()->postTask(
+      BLINK_FROM_HERE,
+      createSameThreadTask(
+          &PresentationRequest::dispatchConnectionAvailableEvent,
+          wrapPersistent(request), wrapPersistent(connection)));
   return connection;
 }
 
 // static
 PresentationConnection* PresentationConnection::take(
     PresentationReceiver* receiver,
     std::unique_ptr<WebPresentationConnectionClient> client) {
   DCHECK(receiver);
   DCHECK(client);
 
@@ skipping 201 matching lines @@
     WebPresentationConnectionState state) {
   if (m_state == state)
     return;
 
   m_state = state;
   switch (m_state) {
     case WebPresentationConnectionState::Connecting:
       NOTREACHED();
       return;
     case WebPresentationConnectionState::Connected:
-      dispatchEvent(Event::create(EventTypeNames::connect));
+      dispatchEventAsync(Event::create(EventTypeNames::connect));
       return;
     case WebPresentationConnectionState::Terminated:
-      dispatchEvent(Event::create(EventTypeNames::terminate));
+      dispatchEventAsync(Event::create(EventTypeNames::terminate));
       return;
     // Closed state is handled in |didClose()|.
     case WebPresentationConnectionState::Closed:
       NOTREACHED();
       return;
   }
   NOTREACHED();
 }
 
 void PresentationConnection::didClose(
     WebPresentationConnectionCloseReason reason,
     const String& message) {
   if (m_state == WebPresentationConnectionState::Closed)
     return;
 
   m_state = WebPresentationConnectionState::Closed;
-  dispatchEvent(PresentationConnectionCloseEvent::create(
+  dispatchEventAsync(PresentationConnectionCloseEvent::create(
       EventTypeNames::close, connectionCloseReasonToString(reason), message));
 }
 
 void PresentationConnection::didFinishLoadingBlob(DOMArrayBuffer* buffer) {
   ASSERT(!m_messages.isEmpty() && m_messages.first()->type == MessageTypeBlob);
   ASSERT(buffer && buffer->buffer());
   // Send the loaded blob immediately here and continue processing the queue.
   WebPresentationClient* client = presentationClient(getExecutionContext());
   if (client)
     client->sendBlobData(m_url, m_id,
                          static_cast<const uint8_t*>(buffer->data()),
                          buffer->byteLength());
 
   m_messages.removeFirst();
   m_blobLoader.clear();
   handleMessageQueue();
 }
 
 void PresentationConnection::didFailLoadingBlob(
     FileError::ErrorCode errorCode) {
   ASSERT(!m_messages.isEmpty() && m_messages.first()->type == MessageTypeBlob);
   // FIXME: generate error message?
   // Ignore the current failed blob item and continue with next items.
   m_messages.removeFirst();
   m_blobLoader.clear();
   handleMessageQueue();
 }
 
+void PresentationConnection::dispatchEventAsync(Event* event) {

[mark a. foltz, 2016/12/07 04:23:55]

Can this be combined into dispatchStateChangeEvent?

[zhaobin, 2016/12/07 19:30:43]

Not sure how to combine them neatly. postTask expects void return type, while
dispatchEvent returns DispatchEventResult. We need some function wrapper to
convert return type.

[mark a. foltz, 2016/12/07 21:32:44]

Ah, got it.  Slight preference to call this method dispatchStateChangeEvent and
to name the method below dispatchEventAsync.

It would also be possible to write a static utility function void
dispatchEventAsync(EventTarget*, Event*) to be used with PostTask here and above
for connectionavailable, but I don't feel strongly.

[zhaobin, 2016/12/08 00:16:46]

Done.

+  getExecutionContext()->postTask(
+      BLINK_FROM_HERE,
+      createSameThreadTask(&PresentationConnection::dispatchStateChangeEvent,
+                           wrapPersistent(this), wrapPersistent(event)));
+}
+
+void PresentationConnection::dispatchStateChangeEvent(Event* event) {
+  dispatchEvent(event);
+}
+
 void PresentationConnection::tearDown() {
   // Cancel current Blob loading if any.
   if (m_blobLoader) {
     m_blobLoader->cancel();
     m_blobLoader.clear();
   }
   m_messages.clear();
 }
 
 }  // namespace blink