Use TaskScheduler instead of WorkerPool in v8_platform.cc.

chrome/test/base/v8_unit_test.h

Index: chrome/test/base/v8_unit_test.h
diff --git a/chrome/test/base/v8_unit_test.h b/chrome/test/base/v8_unit_test.h
index 830da54beb1e5ef69070a49aae95fb6bce7e3ce8..a483b43ae1e17d0251f2927a8e167877710f4a9f 100644
--- a/chrome/test/base/v8_unit_test.h
+++ b/chrome/test/base/v8_unit_test.h
@@ -10,6 +10,7 @@
 
 #include "base/files/file_path.h"
 #include "base/strings/string_piece.h"
+#include "base/test/scoped_async_task_scheduler.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "v8/include/v8.h"
 
@@ -74,6 +75,10 @@ class V8UnitTest : public testing::Test {
   // Initializes paths and libraries.
   void InitPathsAndLibraries();
 
+  // 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_;
+
   // Handle scope that is used throughout the life of this class.
   v8::HandleScope handle_scope_;