Remove mojo::system::Mutex's use of base::internal::LockImpl.

mojo/edk/system/mutex_unittest.cc

 // Copyright 2015 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.
 
 #include "mojo/edk/system/mutex.h"
 
 #include <stdlib.h>
 
 #include "base/threading/platform_thread.h"
 #include "mojo/edk/system/test_utils.h"
@@ skipping 84 matching lines @@
     EpsilonRandomSleep();
     mutex.Unlock();
   }
 
   base::PlatformThread::Join(handle);
 
   EXPECT_GE(acquired, 20);
   EXPECT_GE(thread.acquired(), 20);
 }
 
+TEST(MutexTest, AssertHeld) {
+  Mutex mutex;
+
+#if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
+  // For non-Debug builds, |AssertHeld()| should do nothing.
+  mutex.AssertHeld();
+#else
+  EXPECT_DEATH_IF_SUPPORTED({ mutex.AssertHeld(); }, "Check failed");
+#endif  // defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
+
+  // TODO(vtl): Should also test the case when the mutex is held by another
+  // thread, though this is more annoying since it requires synchronization.
+}
+
 // Test that TryLock() works as expected ---------------------------------------
 
 class TryLockTestThread : public base::PlatformThread::Delegate {
  public:
   explicit TryLockTestThread(Mutex* mutex) : mutex_(mutex), got_lock_(false) {}
 
   void ThreadMain() override MOJO_NO_THREAD_SAFETY_ANALYSIS {
     got_lock_ = mutex_->TryLock();
     if (got_lock_) {
       mutex_->AssertHeld();
@@ skipping 126 matching lines @@
 
   // The destruction of |locker| should unlock |mutex|.
   ASSERT_TRUE(mutex.TryLock());
   mutex.AssertHeld();
   mutex.Unlock();
 }
 
 }  // namespace
 }  // namespace system
 }  // namespace mojo