Implement Permission change observing in Blink.

Source/modules/permissions/PermissionStatus.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 "config.h"
 #include "modules/permissions/PermissionStatus.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "core/dom/Document.h"
+#include "core/events/Event.h"
 #include "modules/EventTargetModulesNames.h"
+#include "modules/permissions/PermissionController.h"
+#include "public/platform/Platform.h"
+#include "public/platform/modules/permissions/WebPermissionClient.h"
 
 namespace blink {
 
+namespace {
+
+// TODO(mlamouri): move this to a common place.
+WebPermissionClient* permissionClient(ExecutionContext* executionContext)
+{
+    if (executionContext->isDocument()) {
+        Document* document = toDocument(executionContext);
+        if (!document->frame())
+            return nullptr;
+        PermissionController* controller = PermissionController::from(*document->frame());
+        return controller ? controller->client() : nullptr;
+    }
+    return Platform::current()->permissionClient();
+}
+
+} // anonymous namespace
+
 // static
 PermissionStatus* PermissionStatus::take(ScriptPromiseResolver* resolver, WebPermissionStatus* status, WebPermissionType type)
 {
-    PermissionStatus* permissionStatus = new PermissionStatus(resolver->executionContext(), *status);
+    PermissionStatus* permissionStatus = PermissionStatus::create(resolver->executionContext(), *status, type);
+    permissionStatus->startListening();
     delete status;
     return permissionStatus;
 }
 
 // static
 void PermissionStatus::dispose(WebPermissionStatus* status)
 {
     delete status;
 }
 
-PermissionStatus::PermissionStatus(ExecutionContext* executionContext, WebPermissionStatus status)
-    : ContextLifecycleObserver(executionContext)
+PermissionStatus* PermissionStatus::create(ExecutionContext* executionContext, WebPermissionStatus status, WebPermissionType type)
+{
+    PermissionStatus* permissionStatus = new PermissionStatus(executionContext, status, type);
+    permissionStatus->suspendIfNeeded();
+    return permissionStatus;
+}
+
+PermissionStatus::PermissionStatus(ExecutionContext* executionContext, WebPermissionStatus status, WebPermissionType type)
+    : ActiveDOMObject(executionContext)
     , m_status(status)
+    , m_type(type)
+    , m_listening(false)
 {
 }
 
 PermissionStatus::~PermissionStatus()
 {
+    stopListening();
 }
 
 const AtomicString& PermissionStatus::interfaceName() const
 {
     return EventTargetNames::PermissionStatus;
 }
 
 ExecutionContext* PermissionStatus::executionContext() const
 {
-    return ContextLifecycleObserver::executionContext();
+    return ActiveDOMObject::executionContext();
 }
 
-DEFINE_TRACE(PermissionStatus)
+void PermissionStatus::permissionChanged(WebPermissionType type, WebPermissionStatus status)
 {
-    RefCountedGarbageCollectedEventTargetWithInlineData<PermissionStatus>::trace(visitor);
-    ContextLifecycleObserver::trace(visitor);
+    ASSERT(m_type == type);
+    if (m_status == status)
+        return;
+
+    m_status = status;
+    dispatchEvent(Event::create(EventTypeNames::change));
+}
+
+bool PermissionStatus::hasPendingActivity() const
+{
+    return m_listening;
+}
+
+void PermissionStatus::resume()
+{
+    startListening();
+}
+
+void PermissionStatus::suspend()
+{
+    stopListening();
+}
+
+void PermissionStatus::stop()
+{
+    stopListening();
+}
+
+void PermissionStatus::startListening()
+{
+    ASSERT(!m_listening);
+
+    WebPermissionClient* client = permissionClient(executionContext());
+    if (!client)
+        return;
+    m_listening = true;
+    client->startListening(m_type, KURL(KURL(), executionContext()->securityOrigin()->toString()), this);
+}
+
+void PermissionStatus::stopListening()
+{
+    if (!m_listening)
+        return;
+
+    ASSERT(executionContext());
+
+    m_listening = false;
+    WebPermissionClient* client = permissionClient(executionContext());
+    if (!client)
+        return;
+    client->stopListening(this);
 }
 
 String PermissionStatus::status() const
 {
     switch (m_status) {
     case WebPermissionStatusGranted:
         return "granted";
     case WebPermissionStatusDenied:
         return "denied";
     case WebPermissionStatusPrompt:
         return "prompt";
     }
 
     ASSERT_NOT_REACHED();
     return "denied";
 }
 
+DEFINE_TRACE(PermissionStatus)
+{
+    RefCountedGarbageCollectedEventTargetWithInlineData<PermissionStatus>::trace(visitor);
+    ActiveDOMObject::trace(visitor);
+}
+
 } // namespace blink