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 1b0e7abf7db8cb2c4df4955f6f5547c63902f14e..ee60a9cbc78858528f3d77e035e0bc11b7e7a57f 100644
--- a/content/public/renderer/content_renderer_client.h
+++ b/content/public/renderer/content_renderer_client.h
@@ -385,6 +385,11 @@ 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 164a4b24b529dd989d6b03a016dbd50242b85e9a..abcad188a5cb4ac543ae8b9908dd8a212330d748 100644
--- a/content/renderer/renderer_blink_platform_impl.cc
+++ b/content/renderer/renderer_blink_platform_impl.cc
@@ -858,6 +858,12 @@ 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 00be5a58e202cf4830397f3386384f7dc8b8e19a..f8cdff26b78a0049414ab369185bd331e488efc3 100644
--- a/content/renderer/renderer_blink_platform_impl.h
+++ b/content/renderer/renderer_blink_platform_impl.h
@@ -186,6 +186,8 @@ 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 f5f0b31af8c18a6e290bcc3605bf43f5fd522b66..72cc5b0ab5a846d1ffa068fa3fa831e221254ce8 100644
--- a/third_party/blink/public/platform/platform.h
+++ b/third_party/blink/public/platform/platform.h
@@ -632,6 +632,8 @@ 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 4a2652c09c84c73ceecb1c0cf6984fca312f1524..06db3025732b43c7e91db439bc81d90819cd27fc 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
@@ -301,6 +301,7 @@ 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());
