Disallow UI/IO thread blocking on any other thread.

base/synchronization/waitable_event_posix.cc

Index: base/synchronization/waitable_event_posix.cc
===================================================================
--- base/synchronization/waitable_event_posix.cc	(revision 133458)
+++ base/synchronization/waitable_event_posix.cc	(working copy)
@@ -5,11 +5,11 @@
 #include <algorithm>
 #include <vector>
 
+#include "base/logging.h"
 #include "base/synchronization/waitable_event.h"
-
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
-#include "base/logging.h"
+#include "base/threading/thread_restrictions.h"
 
 // -----------------------------------------------------------------------------
 // A WaitableEvent on POSIX is implemented as a wait-list. Currently we don't
@@ -158,6 +158,7 @@
 }
 
 bool WaitableEvent::TimedWait(const TimeDelta& max_time) {
+  base::ThreadRestrictions::AssertWaitAllowed();
   const Time end_time(Time::Now() + max_time);
   const bool finite_time = max_time.ToInternalValue() >= 0;
 
@@ -224,6 +225,7 @@
 // static
 size_t WaitableEvent::WaitMany(WaitableEvent** raw_waitables,
                                size_t count) {
+  base::ThreadRestrictions::AssertWaitAllowed();
   DCHECK(count) << "Cannot wait on no events";
 
   // We need to acquire the locks in a globally consistent order. Thus we sort