diff --git a/synchronization/BUILD.gn b/synchronization/BUILD.gn
index 977a571c8da30..9ee7680cc1160 100644
--- a/synchronization/BUILD.gn
+++ b/synchronization/BUILD.gn
@@ -4,16 +4,13 @@
 
 source_set("synchronization") {
   sources = [
-    "debug_thread_checker.h",
     "pipeline.cc",
     "pipeline.h",
     "semaphore.cc",
     "semaphore.h",
   ]
 
-  public_configs = [
-    "$flutter_root:config",
-  ]
+  public_configs = [ "$flutter_root:config" ]
 
   public_deps = [
     "$flutter_root/glue",
diff --git a/synchronization/debug_thread_checker.h b/synchronization/debug_thread_checker.h
deleted file mode 100644
index 69614eb89d217..0000000000000
--- a/synchronization/debug_thread_checker.h
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef FLUTTER_SYNCHRONIZATION_DEBUG_THREAD_CHECKER_H_
-#define FLUTTER_SYNCHRONIZATION_DEBUG_THREAD_CHECKER_H_
-
-#ifndef NDEBUG
-
-#include <pthread.h>
-#include "lib/fxl/synchronization/thread_checker.h"
-
-#define FLUTTER_THREAD_CHECKER_DECLARE(x) ::fxl::ThreadChecker x;
-
-#define FLUTTER_THREAD_CHECKER_CHECK(x) FXL_CHECK(x.IsCreationThreadCurrent());
-
-#else  // NDEBUG
-
-#define FLUTTER_THREAD_CHECKER_DECLARE(x)
-
-#define FLUTTER_THREAD_CHECKER_CHECK(x)
-
-#endif  // NDEBUG
-
-#endif  // FLUTTER_SYNCHRONIZATION_DEBUG_THREAD_CHECKER_H_
diff --git a/synchronization/semaphore.cc b/synchronization/semaphore.cc
index c6e0bdf9e2d53..4dc5f6220e350 100644
--- a/synchronization/semaphore.cc
+++ b/synchronization/semaphore.cc
@@ -15,9 +15,12 @@ namespace flutter {
 class PlatformSemaphore {
  public:
   explicit PlatformSemaphore(uint32_t count)
-      : _sem(dispatch_semaphore_create(count)) {}
+      : _sem(dispatch_semaphore_create(count)), _initial(count) {}
 
   ~PlatformSemaphore() {
+    for (uint32_t i = 0; i < _initial; ++i) {
+      Signal();
+    }
     if (_sem != nullptr) {
       dispatch_release(reinterpret_cast<dispatch_object_t>(_sem));
       _sem = nullptr;
@@ -42,6 +45,7 @@ class PlatformSemaphore {
 
  private:
   dispatch_semaphore_t _sem;
+  const uint32_t _initial;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(PlatformSemaphore);
 };