From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: deepak1556 <hop2deep@gmail.com>
Date: Thu, 17 Oct 2019 18:00:32 -0700
Subject: feat: add hook to notify script ready from WorkerScriptController

In Off-the-main-thread fetch, the WorkerGlobalScope will be in a half
initialized state until the script is finished downloading.

Doc: https://docs.google.com/document/d/1JCv8TD2nPLNC2iRCp_D1OM4I3uTS0HoEobuTymaMqgw/edit

During this stage if the global object is transformed for ex: copying properties
in DidInitializeWorkerContextOnWorkerThread hook then an access to property like
location will result in a crash WorkerGlobalScope::Url() because the script has
not been set with response URL yet.

This issue cannot happen in chromium with existing usage, but can surface when an
embedder tries to integrate Node.js in the worker. Hence, this new hook is proposed
that clearly establishes the worker script is ready for evaluation with the scope
initialized.

diff --git a/content/public/renderer/content_renderer_client.h b/content/public/renderer/content_renderer_client.h
index 025ef3f70a5ae34faf8c6013fbfba171c7f501ac..cea3f3dc05f91927f4ee8be5eec85ec26c8e1e07 100644
--- a/content/public/renderer/content_renderer_client.h
+++ b/content/public/renderer/content_renderer_client.h
@@ -356,6 +356,11 @@ class CONTENT_EXPORT ContentRendererClient {
   virtual void DidInitializeWorkerContextOnWorkerThread(
       v8::Local<v8::Context> context) {}
 
+  // Notifies that a worker script has been downloaded, scope initialized and
+  // ready for evaluation. This function is called from the worker thread.
+  virtual void WorkerScriptReadyForEvaluationOnWorkerThread(
+      v8::Local<v8::Context> context) {}
+
   // Notifies that a worker context will be destroyed. This function is called
   // from the worker thread.
   virtual void WillDestroyWorkerContextOnWorkerThread(
diff --git a/content/renderer/renderer_blink_platform_impl.cc b/content/renderer/renderer_blink_platform_impl.cc
index 2adea2c2edabf3c401e9dcd228f1d57c08066059..7c76b39ea82dd600b72288cccc571660b653b150 100644
--- a/content/renderer/renderer_blink_platform_impl.cc
+++ b/content/renderer/renderer_blink_platform_impl.cc
@@ -961,6 +961,12 @@ void RendererBlinkPlatformImpl::WorkerContextCreated(
       worker);
 }
 
+void RendererBlinkPlatformImpl::WorkerScriptReadyForEvaluation(
+    const v8::Local<v8::Context>& worker) {
+  GetContentClient()->renderer()->WorkerScriptReadyForEvaluationOnWorkerThread(
+      worker);
+}
+
 bool RendererBlinkPlatformImpl::AllowScriptExtensionForServiceWorker(
     const blink::WebSecurityOrigin& script_origin) {
   return GetContentClient()->renderer()->AllowScriptExtensionForServiceWorker(
diff --git a/content/renderer/renderer_blink_platform_impl.h b/content/renderer/renderer_blink_platform_impl.h
index c6e0a728150db2b5af41e12304c88d57e51faa43..7fa7dab64506ddc60e27096412ea7e93608a3394 100644
--- a/content/renderer/renderer_blink_platform_impl.h
+++ b/content/renderer/renderer_blink_platform_impl.h
@@ -208,6 +208,8 @@ class CONTENT_EXPORT RendererBlinkPlatformImpl : public BlinkPlatformImpl {
   void DidStartWorkerThread() override;
   void WillStopWorkerThread() override;
   void WorkerContextCreated(const v8::Local<v8::Context>& worker) override;
+  void WorkerScriptReadyForEvaluation(
+      const v8::Local<v8::Context>& worker) override;
   void WorkerContextWillDestroy(const v8::Local<v8::Context>& worker) override;
   bool AllowScriptExtensionForServiceWorker(
       const blink::WebSecurityOrigin& script_origin) override;
diff --git a/third_party/blink/public/platform/platform.h b/third_party/blink/public/platform/platform.h
index 3cbb1ed9ef65cb9044a76b0a1686f6ab019c87b5..c7694b4a89c16d02f946598bcf66aa3d241af83e 100644
--- a/third_party/blink/public/platform/platform.h
+++ b/third_party/blink/public/platform/platform.h
@@ -714,6 +714,8 @@ class BLINK_PLATFORM_EXPORT Platform {
   virtual void DidStartWorkerThread() {}
   virtual void WillStopWorkerThread() {}
   virtual void WorkerContextCreated(const v8::Local<v8::Context>& worker) {}
+  virtual void WorkerScriptReadyForEvaluation(
+      const v8::Local<v8::Context>& worker) {}
   virtual void WorkerContextWillDestroy(const v8::Local<v8::Context>& worker) {}
   virtual bool AllowScriptExtensionForServiceWorker(
       const WebSecurityOrigin& script_origin) {
diff --git a/third_party/blink/renderer/bindings/core/v8/worker_or_worklet_script_controller.cc b/third_party/blink/renderer/bindings/core/v8/worker_or_worklet_script_controller.cc
index 03288c7b1897ee2c18b80677ee5837246d36568a..fc10bbf3d92c7f88c734d8ecfb20dbc4b72ae200 100644
--- a/third_party/blink/renderer/bindings/core/v8/worker_or_worklet_script_controller.cc
+++ b/third_party/blink/renderer/bindings/core/v8/worker_or_worklet_script_controller.cc
@@ -257,6 +257,7 @@ void WorkerOrWorkletScriptController::PrepareForEvaluation() {
   V8PerContextData* per_context_data = script_state_->PerContextData();
   std::ignore =
       per_context_data->ConstructorForType(global_scope_->GetWrapperTypeInfo());
+  Platform::Current()->WorkerScriptReadyForEvaluation(script_state_->GetContext());
   // Inform V8 that origin trial information is now connected with the context,
   // and V8 can extend the context with origin trial features.
   isolate_->InstallConditionalFeatures(script_state_->GetContext());
