[POC] Implement "module responses map" concept

third_party/WebKit/Source/core/loader/modulescript/WorkletModuleScriptFetcher.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/loader/modulescript/WorkletModuleScriptFetcher.h"
+
+#include "platform/CrossThreadFunctional.h"
+
+namespace blink {
+
+WorkletModuleScriptFetcher::WorkletModuleScriptFetcher(
+    FetchParameters fetch_params,
+    ResourceFetcher* fetcher,
+    Modulator* modulator,
+    WorkletModuleResponsesMapProxy* module_responses_map_proxy)
+    : ModuleScriptFetcher(fetch_params, fetcher, modulator),
+      module_responses_map_proxy_(module_responses_map_proxy) {}
+
+DEFINE_TRACE(WorkletModuleScriptFetcher) {
+  visitor->Trace(module_responses_map_proxy_);
+  ModuleScriptFetcher::Trace(visitor);
+}
+
+void WorkletModuleScriptFetcher::FetchInternal() {
+  module_responses_map_proxy_->ReadEntry(GetRequestUrl(), this);
+}
+
+void WorkletModuleScriptFetcher::OnRead(
+    const ModuleScriptCreationParams& params) {
+  Finalize(params);
+}
+
+void WorkletModuleScriptFetcher::OnFetchNeeded() {
+  // A target module hasn't been fetched yet. Fallback to the regular module
+  // loading path. The module will be cached in NotifyFinished().
+  was_fetched_via_network_ = true;
+  ModuleScriptFetcher::FetchInternal();
+}
+
+void WorkletModuleScriptFetcher::OnFailed() {
+  Finalize(WTF::nullopt);
+}
+
+void WorkletModuleScriptFetcher::Finalize(
+    WTF::Optional<ModuleScriptCreationParams> params) {
+  if (!params.has_value()) {
+    module_responses_map_proxy_->InvalidateEntry(GetRequestUrl());
+  } else if (was_fetched_via_network_) {
+    module_responses_map_proxy_->UpdateEntry(GetRequestUrl(), *params);
+  }
+  ModuleScriptFetcher::Finalize(params);
+}
+
+}  // namespace blink