Worker: Stop calling 'delete this' in EmbeddedSharedWorkerStub::WorkerScriptLoadFailed()

This CL stops calling 'delete this' in WorkerScriptLoadFailed(), and instead
makes sure WorkerContextDestroyed() is called in any case.

This cleanup is necessary for off-the-main-thread shared worker script fetch
because when the feature is enabled, we cannot destroy the worker at
WorkerScriptLoadFailed(), and need to wait for completion of worker thread
termination.

Bug: 924041
Change-Id: Ia4b744f1d7302efbc53fdc09e42e414a7b768865
Reviewed-on: https://chromium-review.googlesource.com/c/1441735Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626970}

content/renderer/shared_worker/embedded_shared_worker_stub.cc

@@ -208,7 +208,6 @@ void EmbeddedSharedWorkerStub::WorkerScriptLoaded() {
 void EmbeddedSharedWorkerStub::WorkerScriptLoadFailed() {
   host_->OnScriptLoadFailed();
   pending_channels_.clear();
-  delete this;
 }
 
 void EmbeddedSharedWorkerStub::WorkerScriptEvaluated(bool success) {

content/renderer/shared_worker/embedded_shared_worker_stub.h

@@ -49,10 +49,7 @@ struct NavigationResponseOverrideParameters;
 // A stub class to receive IPC from browser process and talk to
 // blink::WebSharedWorker. Implements blink::WebSharedWorkerClient.
 // This class is self-destructed (no one explicitly owns this). It deletes
-// itself when either one of following methods is called by
-// blink::WebSharedWorker:
-// - WorkerScriptLoadFailed() or
-// - WorkerContextDestroyed()
+// itself when WorkerContextDestroyed() is called by blink::WebSharedWorker.
 //
 // This class owns blink::WebSharedWorker.
 class EmbeddedSharedWorkerStub : public blink::WebSharedWorkerClient,

third_party/blink/renderer/core/exported/web_shared_worker_impl.cc

@@ -98,6 +98,9 @@ void WebSharedWorkerImpl::TerminateWorkerThread() {
   asked_to_terminate_ = true;
   if (shadow_page_ && !shadow_page_->WasInitialized()) {
     client_->WorkerScriptLoadFailed();
+    // The worker thread hasn't been started yet. Immediately notify the client
+    // of worker termination.
+    client_->WorkerContextDestroyed();
     // |this| is deleted at this point.
     return;
   }
@@ -105,6 +108,9 @@ void WebSharedWorkerImpl::TerminateWorkerThread() {
     main_script_loader_->Cancel();
     main_script_loader_ = nullptr;
     client_->WorkerScriptLoadFailed();
+    // The worker thread hasn't been started yet. Immediately notify the client
+    // of worker termination.
+    client_->WorkerContextDestroyed();
     // |this| is deleted at this point.
     return;
   }
@@ -166,6 +172,13 @@ void WebSharedWorkerImpl::DidFetchScript() {
   client_->WorkerScriptLoaded();
 }
 
+void WebSharedWorkerImpl::DidFailToFetchClassicScript() {
+  DCHECK(IsMainThread());
+  client_->WorkerScriptLoadFailed();
+  TerminateWorkerThread();
+  // DidTerminateWorkerThread() will be called asynchronously.
+}
+
 void WebSharedWorkerImpl::DidEvaluateClassicScript(bool success) {
   DCHECK(IsMainThread());
   client_->WorkerScriptEvaluated(success);
@@ -258,7 +271,11 @@ void WebSharedWorkerImpl::OnScriptLoaderFinished() {
     return;
   if (main_script_loader_->Failed()) {
     main_script_loader_->Cancel();
+    main_script_loader_ = nullptr;
     client_->WorkerScriptLoadFailed();
+    // The worker thread hasn't been started yet. Immediately notify the client
+    // of worker termination.
+    client_->WorkerContextDestroyed();
     // |this| is deleted at this point.
     return;
   }

third_party/blink/renderer/core/exported/web_shared_worker_impl.h

@@ -110,6 +110,7 @@ class CORE_EXPORT WebSharedWorkerImpl final : public WebSharedWorker,
   // Callback methods for SharedWorkerReportingProxy.
   void CountFeature(WebFeature);
   void DidFetchScript();
+  void DidFailToFetchClassicScript();
   void DidEvaluateClassicScript(bool success);
   void DidCloseWorkerGlobalScope();
   void DidTerminateWorkerThread();

third_party/blink/renderer/core/workers/shared_worker_reporting_proxy.cc

@@ -75,9 +75,15 @@ void SharedWorkerReportingProxy::DidFetchScript() {
 }
 
 void SharedWorkerReportingProxy::DidFailToFetchClassicScript() {
+  // TODO(nhiroki): Add a runtime flag check for off-the-main-thread shared
+  // worker script fetch. This function should be called only when the flag is
+  // enabled (https://crbug.com/924041).
   DCHECK(!IsMainThread());
-  // TODO(nhiroki): Dispatch an error event at the SharedWorker object in the
-  // parent document.
+  PostCrossThreadTask(
+      *parent_execution_context_task_runners_->Get(TaskType::kInternalDefault),
+      FROM_HERE,
+      CrossThreadBind(&WebSharedWorkerImpl::DidFailToFetchClassicScript,
+                      CrossThreadUnretained(worker_)));
 }
 
 void SharedWorkerReportingProxy::DidFailToFetchModuleScript() {