Worklet: Enable module script loading for main thread worklets

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

Index: third_party/WebKit/Source/core/workers/WorkletModuleTreeClient.cpp
diff --git a/third_party/WebKit/Source/core/workers/WorkletModuleTreeClient.cpp b/third_party/WebKit/Source/core/workers/WorkletModuleTreeClient.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..829ecd52081120cf4cd53f150332206e0d3460d3
--- /dev/null
+++ b/third_party/WebKit/Source/core/workers/WorkletModuleTreeClient.cpp
@@ -0,0 +1,47 @@
+// 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/WorkletModuleTreeClient.h"
+
+#include "core/dom/ModuleScript.h"
+
+namespace blink {
+
+WorkletModuleTreeClient::WorkletModuleTreeClient(
+    Modulator* modulator,
+    WorkletPendingTasks* pending_tasks)
+    : modulator_(modulator), pending_tasks_(pending_tasks) {}
+
+// Implementation of the second half of the "fetch and invoke a worklet script"
+// algorithm:
+// https://drafts.css-houdini.org/worklets/#fetch-and-invoke-a-worklet-script
+void WorkletModuleTreeClient::NotifyModuleTreeLoadFinished(
+    ModuleScript* module_script) {
+  DCHECK(IsMainThread());
+  if (!module_script) {
+    // Step 3: "If script is null, then queue a task on outsideSettings's
+    // responsible event loop to run these steps:"
+    // The steps are implemented in WorkletPendingTasks::Abort().
+    // TODO(nhiroki): Queue a task instead of executing this here.
+    pending_tasks_->Abort();
+    return;
+  }
+
+  // Step 4: "Run a module script given script."
+  modulator_->ExecuteModule(module_script);
+
+  // Step 5: "Queue a task on outsideSettings's responsible event loop to run
+  // these steps:"
+  // The steps are implemented in WorkletPendingTasks::DecrementCounter().
+  // TODO(nhiroki): Queue a task instead of executing this here.
+  pending_tasks_->DecrementCounter();
+};
+
+DEFINE_TRACE(WorkletModuleTreeClient) {
+  visitor->Trace(modulator_);
+  visitor->Trace(pending_tasks_);
+  ModuleTreeClient::Trace(visitor);
+}
+
+}  // namespace blink