Revert "[api] Add API callback setter for the SAB origin trial"

This reverts commit bc1eb7b4.

Reason for revert: https://ci.chromium.org/ui/p/chromium/builders/try/android-pie-arm64-rel/369203/overview

Original change's description:
> [api] Add API callback setter for the SAB origin trial
>
> This change makes it possible to enable SharedArrayBuffer per Context,
> controlling whether it should be enabled or not with a callback. The
> previous implementation of the reverse origin trial for
> SharedArrayBuffer was broken, since the feature could only be enabled
> globally per process, and only if the feature flag is set early enough
> in the v8 initialization. This does not play well with how origin
> trials work.
>
> The implementation is similar to the callbacks that already exist for
> the origin trials for WebAssembly simd and exceptions.
>
> SharedArrayBuffer is still controlled by the flag
> harmony_sharedarraybuffer. If that flag is disabled, then
> SharedArrayBuffer is disabled unconditionally. On top of that, this CL
> introduces a new flag for enabling SharedArrayBuffer per context. If
> that flag is set, a callback is used to determine whether
> SharedArrayBuffer should be enabled.
>
>
> Note that this only controls whether the SharedArrayBuffer constructor
> should be exposed on the global object or not. It is always possible
> to construct a SharedArrayBuffer using
>
>   new WebAssembly.Memory({
>     shared:true, initial:0, maximum:0 }).buffer.constructor;
>
>
> There are few things which I do not like of this approach, but I did
> not have better ideas:
>
> 1. The complex logic of dobule flag + callback. However, this seemed
> the best way to me to not break embedders which rely on that flag
> being enabled by default.
>
> 2. The fact that what actually matters is just whether the callback
> returns `true` once. It would be good to check that the callback gives
> a consistent return value, or to provide a better API that cannot be
> missunderstood.
>
>
> Bug: chromium:923807,chromium:1071424,chromium:1138860
> Change-Id: Ibe3776fad4d3bff5dda9066967e4b20328014266
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2867473
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Antonio Sartori <antoniosartori@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74378}

Bug: chromium:923807
Bug: chromium:1071424
Bug: chromium:1138860
Change-Id: Iec678dee130db891c2096e47bc072a5d77ae9476
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2874403
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Lutz Vahl <vahl@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74404}

include/v8.h

@@ -7590,10 +7590,6 @@ using WasmSimdEnabledCallback = bool (*)(Local<Context> context);
 // --- Callback for checking if WebAssembly exceptions are enabled ---
 using WasmExceptionsEnabledCallback = bool (*)(Local<Context> context);
 
-// --- Callback for checking if the SharedArrayBuffer constructor is enabled ---
-using SharedArrayBufferConstructorEnabledCallback =
-    bool (*)(Local<Context> context);
-
 // --- Garbage Collection Callbacks ---
 
 /**
@@ -9543,9 +9539,6 @@ class V8_EXPORT Isolate {
 
   void SetWasmExceptionsEnabledCallback(WasmExceptionsEnabledCallback callback);
 
-  void SetSharedArrayBufferConstructorEnabledCallback(
-      SharedArrayBufferConstructorEnabledCallback callback);
-
   /**
    * This function can be called by the embedder to signal V8 that the dynamic
    * enabling of features has finished. V8 can now set up dynamically added

src/api/api.cc

@@ -5930,7 +5930,6 @@ void V8::GetSharedMemoryStatistics(SharedMemoryStatistics* statistics) {
 
 void V8::SetIsCrossOriginIsolated() {
   i::FLAG_harmony_sharedarraybuffer = true;
-  i::FLAG_enable_sharedarraybuffer_per_context = false;
 #if V8_ENABLE_WEBASSEMBLY
   i::FLAG_experimental_wasm_threads = true;
 #endif  // V8_ENABLE_WEBASSEMBLY
@@ -8997,18 +8996,13 @@ CALLBACK_SETTER(WasmSimdEnabledCallback, WasmSimdEnabledCallback,
 CALLBACK_SETTER(WasmExceptionsEnabledCallback, WasmExceptionsEnabledCallback,
                 wasm_exceptions_enabled_callback)
 
-CALLBACK_SETTER(SharedArrayBufferConstructorEnabledCallback,
-                SharedArrayBufferConstructorEnabledCallback,
-                sharedarraybuffer_constructor_enabled_callback)
-
 void Isolate::InstallConditionalFeatures(Local<Context> context) {
-  v8::HandleScope handle_scope(this);
-  v8::Context::Scope context_scope(context);
-  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
-  isolate->InstallConditionalFeatures(Utils::OpenHandle(*context));
 #if V8_ENABLE_WEBASSEMBLY
   if (i::FLAG_expose_wasm) {
-    i::WasmJs::InstallConditionalFeatures(isolate, Utils::OpenHandle(*context));
+    v8::HandleScope handle_scope(this);
+    v8::Context::Scope context_scope(context);
+    i::WasmJs::InstallConditionalFeatures(reinterpret_cast<i::Isolate*>(this),
+                                          Utils::OpenHandle(*context));
   }
 #endif  // V8_ENABLE_WEBASSEMBLY
 }

src/execution/isolate.cc

@@ -2577,29 +2577,6 @@ void Isolate::SetAbortOnUncaughtExceptionCallback(
   abort_on_uncaught_exception_callback_ = callback;
 }
 
-void Isolate::InstallConditionalFeatures(Handle<Context> context) {
-  Handle<JSGlobalObject> global = handle(context->global_object(), this);
-  Handle<String> sab_name = factory()->SharedArrayBuffer_string();
-  if (!JSReceiver::HasProperty(global, sab_name).FromMaybe(true)) {
-    if (IsSharedArrayBufferConstructorEnabled(context)) {
-      JSObject::AddProperty(this, global, factory()->SharedArrayBuffer_string(),
-                            shared_array_buffer_fun(), DONT_ENUM);
-    }
-  }
-}
-
-bool Isolate::IsSharedArrayBufferConstructorEnabled(Handle<Context> context) {
-  if (!FLAG_harmony_sharedarraybuffer) return false;
-
-  if (!FLAG_enable_sharedarraybuffer_per_context) return true;
-
-  if (sharedarraybuffer_constructor_enabled_callback()) {
-    v8::Local<v8::Context> api_context = v8::Utils::ToLocal(context);
-    return sharedarraybuffer_constructor_enabled_callback()(api_context);
-  }
-  return false;
-}
-
 bool Isolate::IsWasmSimdEnabled(Handle<Context> context) {
 #if V8_ENABLE_WEBASSEMBLY
   if (wasm_simd_enabled_callback()) {

src/execution/isolate.h

@@ -434,8 +434,6 @@ using DebugObjectCache = std::vector<Handle<HeapObject>>;
   V(AllowWasmCodeGenerationCallback, allow_wasm_code_gen_callback, nullptr)   \
   V(ExtensionCallback, wasm_module_callback, &NoExtension)                    \
   V(ExtensionCallback, wasm_instance_callback, &NoExtension)                  \
-  V(SharedArrayBufferConstructorEnabledCallback,                              \
-    sharedarraybuffer_constructor_enabled_callback, nullptr)                  \
   V(WasmStreamingCallback, wasm_streaming_callback, nullptr)                  \
   V(WasmLoadSourceMapCallback, wasm_load_source_map_callback, nullptr)        \
   V(WasmSimdEnabledCallback, wasm_simd_enabled_callback, nullptr)             \
@@ -687,10 +685,6 @@ class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
   inline void set_pending_exception(Object exception_obj);
   inline void clear_pending_exception();
 
-  void InstallConditionalFeatures(Handle<Context> context);
-
-  bool IsSharedArrayBufferConstructorEnabled(Handle<Context> context);
-
   bool IsWasmSimdEnabled(Handle<Context> context);
   bool AreWasmExceptionsEnabled(Handle<Context> context);
 

src/flags/flag-definitions.h

@@ -340,13 +340,6 @@ HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
 DEFINE_BOOL(builtin_subclassing, true,
             "subclassing support in built-in methods")
 
-// If the following flag is set to `true`, the SharedArrayBuffer constructor is
-// enabled per context depending on the callback set via
-// `SetSharedArrayBufferConstructorEnabledCallback`. If no callback is set, the
-// SharedArrayBuffer constructor is disabled.
-DEFINE_BOOL(enable_sharedarraybuffer_per_context, false,
-            "enable the SharedArrayBuffer constructor per context")
-
 #ifdef V8_INTL_SUPPORT
 DEFINE_BOOL(icu_timezone_data, true, "get information about timezones from ICU")
 #endif

src/init/bootstrapper.cc

@@ -4405,10 +4405,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_intl_dateformat_day_period)
 #undef EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE
 
 void Genesis::InitializeGlobal_harmony_sharedarraybuffer() {
-  if (!FLAG_harmony_sharedarraybuffer ||
-      FLAG_enable_sharedarraybuffer_per_context) {
-    return;
-  }
+  if (!FLAG_harmony_sharedarraybuffer) return;
 
   Handle<JSGlobalObject> global(native_context()->global_object(), isolate());
 

test/cctest/test-api.cc

@@ -29071,52 +29071,3 @@ THREADED_TEST(MicrotaskQueueOfContext) {
       microtask_queue.get());
   CHECK_EQ(context->GetMicrotaskQueue(), microtask_queue.get());
 }
-
-namespace {
-
-bool sab_constructor_enabled_value = false;
-
-bool MockSabConstructorEnabledCallback(v8::Local<v8::Context>) {
-  return sab_constructor_enabled_value;
-}
-
-}  // namespace
-
-TEST(TestSetSabConstructorEnabledCallback) {
-  LocalContext env;
-  v8::Isolate* isolate = env->GetIsolate();
-  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-  v8::HandleScope scope(isolate);
-  v8::Local<v8::Context> context = v8::Context::New(CcTest::isolate());
-  i::Handle<i::Context> i_context = v8::Utils::OpenHandle(*context);
-
-  // {Isolate::IsSharedArrayBufferConstructorEnabled} calls the callback set by
-  // the embedder if such a callback exists. Otherwise it returns
-  // {FLAG_harmony_sharedarraybuffer}. First we test that the flag is returned
-  // correctly if no callback is set. Then we test that the flag is ignored if
-  // the callback is set.
-
-  i::FLAG_harmony_sharedarraybuffer = false;
-  i::FLAG_enable_sharedarraybuffer_per_context = false;
-  CHECK(!i_isolate->IsSharedArrayBufferConstructorEnabled(i_context));
-
-  i::FLAG_harmony_sharedarraybuffer = false;
-  i::FLAG_enable_sharedarraybuffer_per_context = false;
-  CHECK(!i_isolate->IsSharedArrayBufferConstructorEnabled(i_context));
-
-  i::FLAG_harmony_sharedarraybuffer = true;
-  i::FLAG_enable_sharedarraybuffer_per_context = false;
-  CHECK(i_isolate->IsSharedArrayBufferConstructorEnabled(i_context));
-
-  i::FLAG_harmony_sharedarraybuffer = true;
-  i::FLAG_enable_sharedarraybuffer_per_context = true;
-  CHECK(!i_isolate->IsSharedArrayBufferConstructorEnabled(i_context));
-
-  isolate->SetSharedArrayBufferConstructorEnabledCallback(
-      MockSabConstructorEnabledCallback);
-  sab_constructor_enabled_value = false;
-  CHECK(!i_isolate->IsSharedArrayBufferConstructorEnabled(i_context));
-
-  sab_constructor_enabled_value = true;
-  CHECK(i_isolate->IsSharedArrayBufferConstructorEnabled(i_context));
-}