[cleanup] Deprecate EnsureEventLoopInitialized

Due to a recent refactoring the function EnsureEventLoopInitialized on
the default platform became obsolete. It does not contain a single line
of code. With this CL we prepare the removal of this function from the
V8 platform API.

R=rmcilroy@chromium.org

Bug: v8:7310
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng;master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: If4d54cd989f8df2f40b322be3b67bb8a482398d0
Reviewed-on: https://chromium-review.googlesource.com/934221
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51635}

include/libplatform/libplatform.h

@@ -62,8 +62,10 @@ V8_PLATFORM_EXPORT bool PumpMessageLoop(
     v8::Platform* platform, v8::Isolate* isolate,
     MessageLoopBehavior behavior = MessageLoopBehavior::kDoNotWait);
 
-V8_PLATFORM_EXPORT void EnsureEventLoopInitialized(v8::Platform* platform,
-                                                   v8::Isolate* isolate);
+V8_PLATFORM_EXPORT V8_DEPRECATE_SOON(
+    "This function has become obsolete and is essentially a nop",
+    void EnsureEventLoopInitialized(v8::Platform* platform,
+                                    v8::Isolate* isolate));
 
 /**
  * Runs pending idle tasks for at most |idle_time_in_seconds| seconds.

src/d8.cc

@@ -2502,8 +2502,7 @@ void SourceGroup::ExecuteInThread() {
       Shell::HostImportModuleDynamically);
   isolate->SetHostInitializeImportMetaObjectCallback(
       Shell::HostInitializeImportMetaObject);
-
-  Shell::EnsureEventLoopInitialized(isolate);
+  Shell::SetWaitUntilDone(isolate, false);
   D8Console console(isolate);
   debug::SetConsoleDelegate(isolate, &console);
   for (int i = 0; i < Shell::options.stress_runs; ++i) {
@@ -2925,7 +2924,7 @@ int Shell::RunMain(Isolate* isolate, int argc, char* argv[], bool last_run) {
     options.isolate_sources[i].StartExecuteInThread();
   }
   {
-    EnsureEventLoopInitialized(isolate);
+    SetWaitUntilDone(isolate, false);
     if (options.lcov_file) {
       debug::Coverage::SelectMode(isolate, debug::Coverage::kBlockCount);
     }
@@ -2976,11 +2975,6 @@ void Shell::CollectGarbage(Isolate* isolate) {
   }
 }
 
-void Shell::EnsureEventLoopInitialized(Isolate* isolate) {
-  v8::platform::EnsureEventLoopInitialized(GetDefaultPlatform(), isolate);
-  SetWaitUntilDone(isolate, false);
-}
-
 void Shell::SetWaitUntilDone(Isolate* isolate, bool value) {
   base::LockGuard<base::Mutex> guard(isolate_status_lock_.Pointer());
   if (isolate_status_.count(isolate) == 0) {

src/d8.h

@@ -369,7 +369,6 @@ class Shell : public i::AllStatic {
   static void OnExit(Isolate* isolate);
   static void CollectGarbage(Isolate* isolate);
   static bool EmptyMessageQueues(Isolate* isolate);
-  static void EnsureEventLoopInitialized(Isolate* isolate);
   static void CompleteMessageLoop(Isolate* isolate);
 
   static std::unique_ptr<SerializationData> SerializeValue(

test/fuzzer/fuzzer-support.cc

@@ -33,8 +33,6 @@ FuzzerSupport::FuzzerSupport(int* argc, char*** argv) {
     v8::HandleScope handle_scope(isolate_);
     context_.Reset(isolate_, v8::Context::New(isolate_));
   }
-
-  v8::platform::EnsureEventLoopInitialized(platform_.get(), isolate_);
 }
 
 FuzzerSupport::~FuzzerSupport() {