Introduce ModulePendingScript

BUG=594639

Review-Url: https://codereview.chromium.org/2815453006
Cr-Commit-Position: refs/heads/master@{#464627}

third_party/WebKit/Source/core/dom/BUILD.gn

@@ -197,6 +197,8 @@ blink_core_sources("dom") {
     "Modulator.h",
     "ModuleMap.cpp",
     "ModuleMap.h",
+    "ModulePendingScript.cpp",
+    "ModulePendingScript.h",
     "ModuleScript.cpp",
     "ModuleScript.h",
     "MutationCallback.h",

third_party/WebKit/Source/core/dom/Modulator.h

@@ -34,6 +34,13 @@ class SingleModuleClient : public GarbageCollectedMixin {
   virtual void NotifyModuleLoadFinished(ModuleScript*) = 0;
 };
 
+// A ModuleTreeClient is notified when a module script and its whole descendent
+// tree load is complete.
+class ModuleTreeClient : public GarbageCollectedMixin {
+ public:
+  virtual void NotifyModuleTreeLoadFinished(ModuleScript*) = 0;
+};
+
 // spec: "top-level module fetch flag"
 // https://html.spec.whatwg.org/multipage/webappapis.html#fetching-scripts-is-top-level
 enum class ModuleGraphLevel { kTopLevelModuleFetch, kDependentModuleFetch };

third_party/WebKit/Source/core/dom/ModulePendingScript.cpp

@@ -0,0 +1,82 @@
+// 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/dom/ModulePendingScript.h"
+
+#include "core/dom/ScriptLoader.h"
+#include "core/frame/LocalFrame.h"
+
+namespace blink {
+
+ModulePendingScriptTreeClient::ModulePendingScriptTreeClient()
+    : module_script_(nullptr), pending_script_(nullptr) {}
+
+void ModulePendingScriptTreeClient::SetPendingScript(
+    ModulePendingScript* pending_script) {
+  DCHECK(!pending_script_);
+  pending_script_ = pending_script;
+
+  if (finished_) {
+    pending_script_->NotifyModuleTreeLoadFinished();
+  }
+}
+
+void ModulePendingScriptTreeClient::NotifyModuleTreeLoadFinished(
+    ModuleScript* module_script) {
+  DCHECK(!(module_script && module_script->InstantiationState() ==
+                                ModuleInstantiationState::kUninstantiated));
+  DCHECK(!finished_);
+  finished_ = true;
+  module_script_ = module_script;
+
+  if (pending_script_)
+    pending_script_->NotifyModuleTreeLoadFinished();
+}
+
+DEFINE_TRACE(ModulePendingScriptTreeClient) {
+  visitor->Trace(module_script_);
+  visitor->Trace(pending_script_);
+  ModuleTreeClient::Trace(visitor);
+}
+
+ModulePendingScript::ModulePendingScript(ScriptElementBase* element,
+                                         ModulePendingScriptTreeClient* client)
+    : PendingScript(element, TextPosition()), module_tree_client_(client) {
+  CHECK(this->GetElement());
+  DCHECK(module_tree_client_);
+  client->SetPendingScript(this);
+}
+
+ModulePendingScript::~ModulePendingScript() {}
+
+void ModulePendingScript::DisposeInternal() {
+  module_tree_client_ = nullptr;
+}
+
+DEFINE_TRACE(ModulePendingScript) {
+  visitor->Trace(module_tree_client_);
+  PendingScript::Trace(visitor);
+}
+
+void ModulePendingScript::NotifyModuleTreeLoadFinished() {
+  CHECK(!IsReady());
+  ready_ = true;
+
+  if (Client())
+    Client()->PendingScriptFinished(this);
+}
+
+Script* ModulePendingScript::GetSource(const KURL& document_url,
+                                       bool& error_occurred) const {
+  CHECK(IsReady());
+  error_occurred = ErrorOccurred();
+  return GetModuleScript();
+}
+
+bool ModulePendingScript::ErrorOccurred() const {
+  CHECK(IsReady());
+  return !GetModuleScript();
+}
+
+}  // namespace blink

third_party/WebKit/Source/core/dom/ModulePendingScript.h

@@ -0,0 +1,98 @@
+// 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.
+
+#ifndef ModulePendingScript_h
+#define ModulePendingScript_h
+
+#include "core/dom/Modulator.h"
+#include "core/dom/ModuleScript.h"
+#include "core/dom/PendingScript.h"
+
+namespace blink {
+
+class ModulePendingScript;
+
+// ModulePendingScriptTreeClient is used to connect from Modulator::FetchTree()
+// to ModulePendingScript. Because ModulePendingScript is created after
+// Modulator::FetchTree() is called, ModulePendingScriptTreeClient is
+// registered as ModuleTreeClient to FetchTree() first, and later
+// ModulePendingScript is supplied to ModulePendingScriptTreeClient via
+// SetPendingScript() and is notified of module tree load finish.
+class ModulePendingScriptTreeClient final
+    : public GarbageCollectedFinalized<ModulePendingScriptTreeClient>,
+      public ModuleTreeClient {
+  USING_GARBAGE_COLLECTED_MIXIN(ModulePendingScriptTreeClient);
+
+ public:
+  static ModulePendingScriptTreeClient* Create() {
+    return new ModulePendingScriptTreeClient();
+  }
+  virtual ~ModulePendingScriptTreeClient() = default;
+
+  void SetPendingScript(ModulePendingScript* client);
+
+  ModuleScript* GetModuleScript() const { return module_script_; }
+
+  DECLARE_TRACE();
+
+ private:
+  ModulePendingScriptTreeClient();
+
+  // Implements ModuleTreeClient
+  void NotifyModuleTreeLoadFinished(ModuleScript*) override;
+
+  bool finished_ = false;
+  Member<ModuleScript> module_script_;
+  Member<ModulePendingScript> pending_script_;
+};
+
+// PendingScript for a module script
+// https://html.spec.whatwg.org/#module-script.
+class CORE_EXPORT ModulePendingScript : public PendingScript {
+ public:
+  static ModulePendingScript* Create(ScriptElementBase* element,
+                                     ModulePendingScriptTreeClient* client) {
+    return new ModulePendingScript(element, client);
+  }
+
+  ~ModulePendingScript() override;
+
+  void NotifyModuleTreeLoadFinished();
+
+  ModuleScript* GetModuleScript() const {
+    return module_tree_client_->GetModuleScript();
+  }
+
+  DECLARE_TRACE();
+
+ private:
+  ModulePendingScript(ScriptElementBase*, ModulePendingScriptTreeClient*);
+
+  // PendingScript
+  ScriptType GetScriptType() const override { return ScriptType::kModule; }
+  Script* GetSource(const KURL& document_url,
+                    bool& error_occurred) const override;
+  bool IsReady() const override { return ready_; }
+  bool IsExternal() const override { return true; }
+  bool ErrorOccurred() const override;
+  bool WasCanceled() const override { return false; }
+
+  void StartStreamingIfPossible(Document*, ScriptStreamer::Type) override {}
+  KURL UrlForClassicScript() const override {
+    NOTREACHED();
+    return KURL();
+  }
+  void RemoveFromMemoryCache() override { NOTREACHED(); }
+
+  void DisposeInternal() override;
+
+  void CheckState() const override {}
+
+  Member<ModulePendingScriptTreeClient> module_tree_client_;
+  bool ready_ = false;
+};
+
+}  // namespace blink
+
+#endif  // ModulePendingScript_h