Set up NaClChromeMainArgs number_of_cores member so apps can size threadpools appropriately

chrome/nacl/nacl_helper_linux.cc

Index: chrome/nacl/nacl_helper_linux.cc
diff --git a/chrome/nacl/nacl_helper_linux.cc b/chrome/nacl/nacl_helper_linux.cc
index 53c2fb30118b87cebbbdedc64f3b1995da8ebbd2..a066db794aa43f3a5a314b5f7a1f41b59442df03 100644
--- a/chrome/nacl/nacl_helper_linux.cc
+++ b/chrome/nacl/nacl_helper_linux.cc
@@ -40,7 +40,8 @@ namespace {
 //   if (!child) {
 // Note: this code doesn't attempt to support SELINUX or the SECCOMP sandbox.
 void BecomeNaClLoader(const std::vector<int>& child_fds,
-                      size_t prereserved_sandbox_size) {
+                      size_t prereserved_sandbox_size,
+                      int number_of_cores) {
   VLOG(1) << "NaCl loader: setting up IPC descriptor";
   // don't need zygote FD any more
   if (HANDLE_EINTR(close(kNaClZygoteDescriptor)) != 0)
@@ -51,6 +52,7 @@ void BecomeNaClLoader(const std::vector<int>& child_fds,
   MessageLoopForIO main_message_loop;
   NaClListener listener;
   listener.set_prereserved_sandbox_size(prereserved_sandbox_size);
+  listener.set_number_of_cores(number_of_cores);
   listener.Listen();
   _exit(0);
 }
@@ -58,7 +60,8 @@ void BecomeNaClLoader(const std::vector<int>& child_fds,
 // Some of this code was lifted from
 // content/browser/zygote_main_linux.cc:ForkWithRealPid()
 void HandleForkRequest(const std::vector<int>& child_fds,
-                       size_t prereserved_sandbox_size) {
+                       size_t prereserved_sandbox_size,
+                       int number_of_cores) {
   VLOG(1) << "nacl_helper: forking";
   pid_t childpid = fork();
   if (childpid < 0) {
@@ -96,7 +99,7 @@ void HandleForkRequest(const std::vector<int>& child_fds,
     if (HANDLE_EINTR(close(child_fds[kNaClParentFDIndex])) != 0)
       LOG(ERROR) << "close(child_fds[kNaClParentFDIndex]) failed";
     if (validack) {
-      BecomeNaClLoader(child_fds, prereserved_sandbox_size);
+      BecomeNaClLoader(child_fds, prereserved_sandbox_size, number_of_cores);
     } else {
       LOG(ERROR) << "Failed to synch with zygote";
     }
@@ -236,6 +239,7 @@ int main(int argc, char* argv[]) {
 #endif
   std::vector<int> empty; // for SendMsg() calls
   size_t prereserved_sandbox_size = CheckReservedAtZero();
+  int number_of_cores = sysconf(_SC_NPROCESSORS_ONLN);
 
   CheckRDebug(argv[0]);
 
@@ -272,7 +276,7 @@ int main(int argc, char* argv[]) {
     } else if (msglen == sizeof(kNaClForkRequest) - 1 &&
                memcmp(buf, kNaClForkRequest, msglen) == 0) {
       if (kNaClParentFDIndex + 1 == fds.size()) {
-        HandleForkRequest(fds, prereserved_sandbox_size);
+        HandleForkRequest(fds, prereserved_sandbox_size, number_of_cores);
         continue;  // fork succeeded. Note: child does not return
       } else {
         LOG(ERROR) << "nacl_helper: unexpected number of fds, got "