base: Fix DCHECK when thread creation fails

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index cfa86d98ce4351137eb9d222af17ed5e7fc30780..12649f85470be716e5418874ffae75dedde8b799 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -133,9 +133,10 @@ MessageLoop::MessageLoop(scoped_ptr<MessagePump> pump)
 }
 
 MessageLoop::~MessageLoop() {
-  // current() could be NULL if this message loop is destructed before it is
-  // bound to a thread.
-  DCHECK(current() == this || !current());
+  // If |pump_| is non-null, this message loop should be the current one on this
+  // thread. Otherwise, this loop is being destructed before it was bound to a
+  // thread, so a different message loop (or no loop at all) may be current.
+  DCHECK((pump_ && current() == this) || current() != this);

[danakj, 2016/01/06 21:03:22]

This would still pass if pump_ && current() != this. I think you want

DCHECK((pump_ && current() == this) || (!pump_ && current() != this))

ya?

[Sami, 2016/01/07 10:46:10]

Ah, right you are. Fixed, thanks.

 
   // iOS just attaches to the loop, it doesn't Run it.
   // TODO(stuartmorgan): Consider wiring up a Detach().
@@ -177,7 +178,8 @@ MessageLoop::~MessageLoop() {
   task_runner_ = NULL;
 
   // OK, now make it so that no one can find us.
-  lazy_tls_ptr.Pointer()->Set(NULL);
+  if (current() == this)

[danakj, 2016/01/06 21:03:22]

Yay for tests :o

[Sami, 2016/01/07 10:46:10]

They're the best.

+    lazy_tls_ptr.Pointer()->Set(nullptr);
 }
 
 // static