Update the tcmalloc chromium branch to r144 (gperftools 2.0), and merge chromium-specific changes.

third_party/tcmalloc/chromium/src/maybe_threads.cc

Index: third_party/tcmalloc/chromium/src/maybe_threads.cc
diff --git a/third_party/tcmalloc/chromium/src/maybe_threads.cc b/third_party/tcmalloc/chromium/src/maybe_threads.cc
index cda1d630328c73e92cccb6cda4bd520da3733eba..15c8a23dcb3509549ef6b45531f2418e988a3cf5 100644
--- a/third_party/tcmalloc/chromium/src/maybe_threads.cc
+++ b/third_party/tcmalloc/chromium/src/maybe_threads.cc
@@ -39,6 +39,7 @@
 #include "config.h"
 #include <assert.h>
 #include <string.h>    // for memcmp
+#include <stdio.h>     // for __isthreaded on FreeBSD
 // We don't actually need strings. But including this header seems to
 // stop the compiler trying to short-circuit our pthreads existence
 // tests and claiming that the address of a function is always
@@ -98,9 +99,28 @@ int perftools_pthread_setspecific(pthread_key_t key, void *val) {
   }
 }
 
+
 static pthread_once_t pthread_once_init = PTHREAD_ONCE_INIT;
 int perftools_pthread_once(pthread_once_t *ctl,
                            void  (*init_routine) (void)) {
+#ifdef __FreeBSD__
+  // On __FreeBSD__, calling pthread_once on a system that is not
+  // linked with -pthread is silently a noop. :-( Luckily, we have a
+  // workaround: FreeBSD exposes __isthreaded in <stdio.h>, which is
+  // set to 1 when the first thread is spawned.  So on those systems,
+  // we can use our own separate pthreads-once mechanism, which is
+  // used until __isthreaded is 1 (which will never be true if the app
+  // is not linked with -pthread).
+  static bool pthread_once_ran_before_threads = false;
+  if (pthread_once_ran_before_threads) {
+    return 0;
+  }
+  if (!__isthreaded) {
+    init_routine();
+    pthread_once_ran_before_threads = true;
+    return 0;
+  }
+#endif
   if (pthread_once) {
     return pthread_once(ctl, init_routine);
   } else {