Worklet: Enqueue tasks into outsideSetting's event loop

third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp

 // Copyright 2017 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 "core/workers/MainThreadWorklet.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptSourceCode.h"
 #include "bindings/core/v8/V8BindingForCore.h"
 #include "core/frame/LocalFrame.h"
 #include "core/workers/WorkletGlobalScopeProxy.h"
 #include "core/workers/WorkletPendingTasks.h"
+#include "platform/WebTaskRunner.h"
 #include "platform/wtf/WTF.h"
 #include "public/platform/WebURLRequest.h"
 
 namespace blink {
 
 namespace {
 
 WebURLRequest::FetchCredentialsMode ParseCredentialsOption(
     const String& credentials_option) {
   if (credentials_option == "omit")
@@ skipping 26 matching lines @@
   DCHECK(IsMainThread());
   if (!GetExecutionContext())
     return;
 
   // Step 6: "Let credentialOptions be the credentials member of options."
   // TODO(nhiroki): Add tests for credentialOptions (https://crbug.com/710837).
   WebURLRequest::FetchCredentialsMode credentials_mode =
       ParseCredentialsOption(options.credentials());
 
   // Step 7: "Let outsideSettings be the relevant settings object of this."
-  // TODO(nhiroki): outsideSettings will be used for posting a task to the
-  // document's responsible event loop. We could use a task runner for the
-  // purpose.
+  // In the specification, outsideSettings is used for posting a task to the
+  // document's responsible event loop. In our implementation, WebTaskRunner
+  // does this.

[kinuko, 2017/05/30 04:38:52]

Now the last part of this comment reads a bit weird. Maybe say something like:
'... a task to the document's responsible event loop. In our implementation we
use the document's UnspecedLoading task runner as that is what we commonly use
for module loading' ?

[nhiroki, 2017/05/30 05:25:30]

Done.

+  RefPtr<WebTaskRunner> parent_frame_task_runner =
+      TaskRunnerHelper::Get(TaskType::kUnspecedLoading, GetExecutionContext());
 
   // Step 8: "Let moduleResponsesMap be worklet's module responses map."
   // TODO(nhiroki): Implement moduleResponsesMap (https://crbug.com/627945).
 
   // Step 9: "Let workletGlobalScopeType be worklet's worklet global scope
   // type."
   // workletGlobalScopeType is encoded into the class name (e.g., PaintWorklet).
 
   // Step 10: "If the worklet's WorkletGlobalScopes is empty, run the following
   // steps:"
@@ skipping 12 matching lines @@
       new WorkletPendingTasks(GetNumberOfGlobalScopes(), resolver);
 
   // Step 12: "For each workletGlobalScope in the worklet's
   // WorkletGlobalScopes, queue a task on the workletGlobalScope to fetch and
   // invoke a worklet script given workletGlobalScope, moduleURLRecord,
   // moduleResponsesMap, credentialOptions, outsideSettings, pendingTaskStruct,
   // and promise."
   // TODO(nhiroki): Queue a task instead of executing this here.
   for (const auto& proxy : proxies_) {
     proxy->FetchAndInvokeScript(module_url_record, credentials_mode,
-                                pending_tasks);
+                                parent_frame_task_runner, pending_tasks);
   }
 }
 
 void MainThreadWorklet::ContextDestroyed(ExecutionContext* execution_context) {
   DCHECK(IsMainThread());
   for (const auto& proxy : proxies_)
     proxy->TerminateWorkletGlobalScope();
 }
 
 DEFINE_TRACE(MainThreadWorklet) {
   Worklet::Trace(visitor);
 }
 
 }  // namespace blink