Recently I tried to debug CPU profiling on Chrome.

I've found that profiling is not working in Debug version.
The actual problem is that sandbox/playgroung configuration is wrong and tgkill syscalls are disallowed.

This patch will make such cases more clear.

Review URL: https://codereview.chromium.org/11961037
Patch from Eugene Klyuchnikov <eustas@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13411 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/platform-linux.cc

@@ -1208,7 +1208,9 @@ class SignalSender : public Thread {
 #if defined(ANDROID)
     syscall(__NR_tgkill, vm_tgid_, tid, SIGPROF);
 #else
-    syscall(SYS_tgkill, vm_tgid_, tid, SIGPROF);
+    int result = syscall(SYS_tgkill, vm_tgid_, tid, SIGPROF);
+    USE(result);
+    ASSERT(result == 0);
 #endif
   }