Use TaskScheduler instead of WorkerPool in v8_platform.cc.

extensions/renderer/gc_callback_unittest.cc

Index: extensions/renderer/gc_callback_unittest.cc
diff --git a/extensions/renderer/gc_callback_unittest.cc b/extensions/renderer/gc_callback_unittest.cc
index e6dfab625ae01aa8b05b4a87f1eef3dc2ab6bcbc..2000c504b51c6b42c5c4cca63165c7710ece98de 100644
--- a/extensions/renderer/gc_callback_unittest.cc
+++ b/extensions/renderer/gc_callback_unittest.cc
@@ -7,6 +7,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_async_task_scheduler.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_set.h"
 #include "extensions/common/features/feature.h"
@@ -34,8 +35,6 @@ class GCCallbackTest : public testing::Test {
   GCCallbackTest() : script_context_set_(&active_extensions_) {}
 
  protected:
-  base::MessageLoop& message_loop() { return message_loop_; }
-
   ScriptContextSet& script_context_set() { return script_context_set_; }
 
   v8::Local<v8::Context> v8_context() {
@@ -72,6 +71,11 @@ class GCCallbackTest : public testing::Test {
   }
 
   base::MessageLoop message_loop_;
+
+  // Required by gin::V8Platform::CallOnBackgroundThread(). Can't be a
+  // ScopedTaskScheduler because v8 synchronously waits for tasks to run.
+  base::test::ScopedAsyncTaskScheduler scoped_async_task_scheduler_;
+
   ScopedWebFrame web_frame_;  // (this will construct the v8::Isolate)
   // ExtensionsRendererClient is a dependency of ScriptContextSet.
   TestExtensionsRendererClient extensions_renderer_client_;