Start sampler for the runtime profiler even when we can't setup a signal handler.

Review URL: http://codereview.chromium.org/6625013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7059 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/platform-linux.cc

@@ -584,7 +584,9 @@ static void* ThreadEntry(void* arg) {
   // This is also initialized by the first argument to pthread_create() but we
   // don't know which thread will run first (the original thread or the new
   // one) so we initialize it here too.
-  prctl(PR_SET_NAME, reinterpret_cast<unsigned long>(thread->name()), 0, 0, 0);
+  prctl(PR_SET_NAME,
+        reinterpret_cast<unsigned long>(thread->name()),  // NOLINT
+        0, 0, 0);
   thread->thread_handle_data()->thread_ = pthread_self();
   ASSERT(thread->IsValid());
   thread->Run();
@@ -871,6 +873,7 @@ class Sampler::PlatformData : public Malloced {
   }
 
   void SendProfilingSignal() {
+    if (!signal_handler_installed_) return;
     // Glibc doesn't provide a wrapper for tgkill(2).
     syscall(SYS_tgkill, vm_tgid_, vm_tid_, SIGPROF);
   }
@@ -937,8 +940,8 @@ void Sampler::Start() {
   sa.sa_sigaction = ProfilerSignalHandler;
   sigemptyset(&sa.sa_mask);
   sa.sa_flags = SA_RESTART | SA_SIGINFO;
-  if (sigaction(SIGPROF, &sa, &data_->old_signal_handler_) != 0) return;
-  data_->signal_handler_installed_ = true;
+  data_->signal_handler_installed_ =
+      sigaction(SIGPROF, &sa, &data_->old_signal_handler_) == 0;
 
   // Start a thread that sends SIGPROF signal to VM thread.
   // Sending the signal ourselves instead of relying on itimer provides