Add joinable option to SimpleThread::Options as was just done for Thread.

base/threading/thread_restrictions.h

 // Copyright (c) 2012 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 BASE_THREADING_THREAD_RESTRICTIONS_H_
 #define BASE_THREADING_THREAD_RESTRICTIONS_H_
 
 #include "base/base_export.h"
 #include "base/logging.h"
 #include "base/macros.h"
 
+#if DCHECK_IS_ON()

[jam, 2016/08/10 17:34:36]

tangent: it's odd that this is DCHECK_IS_ON() instead of DCHECK_IS_ON, why is
that?

[jam, 2016/08/10 17:35:18]

nvm i see
https://chromium.googlesource.com/chromium/src/+/e649f573a38b00bb20fe09250982...
now :)

+// For DelegateSimpleThread::Delegate.
+#include "base/threading/simple_thread.h"
+#endif
+
 class BrowserProcessImpl;
 class HistogramSynchronizer;
 class NativeBackendKWallet;
 class ScopedAllowWaitForLegacyWebViewApi;
 
 namespace cc {
 class CompletionEvent;
 class SingleThreadTaskGraphRunner;
 }
 namespace chromeos {
@@ skipping 180 matching lines @@
   friend class SimpleThread;
   friend class Thread;
   friend class ThreadTestHelper;
   friend class PlatformThread;
   friend class android::JavaHandlerThread;
   friend class mojo::common::MessagePumpMojo;
   friend class mojo::SyncCallRestrictions;
   friend class ui::CommandBufferClientImpl;
   friend class ui::CommandBufferLocal;
   friend class ui::GpuState;
+  // Only required for DCHECK assertions.
+#if DCHECK_IS_ON()
+  friend class DelegateSimpleThread::Delegate;
+#endif
 
   // END ALLOWED USAGE.
   // BEGIN USAGE THAT NEEDS TO BE FIXED.
   friend class ::chromeos::BlockingMethodCaller;  // http://crbug.com/125360
   friend class ::chromeos::system::StatisticsProviderImpl;  // http://crbug.com/125385
   friend class chrome_browser_net::Predictor;     // http://crbug.com/78451
   friend class
       content::BrowserGpuChannelHostFactory;      // http://crbug.com/125248
   friend class
       content::BrowserGpuMemoryBufferManager;     // http://crbug.com/420368
@@ skipping 33 matching lines @@
 
     DISALLOW_COPY_AND_ASSIGN(ScopedAllowWait);
   };
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ThreadRestrictions);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_THREAD_RESTRICTIONS_H_