Revert 110557 - Use nacl::CreateMemoryObject to create dynamic code shared memory object

chrome/browser/nacl_host/nacl_process_host.cc

Index: chrome/browser/nacl_host/nacl_process_host.cc
===================================================================
--- chrome/browser/nacl_host/nacl_process_host.cc	(revision 110570)
+++ chrome/browser/nacl_host/nacl_process_host.cc	(working copy)
@@ -501,18 +501,22 @@
 #if defined(OS_POSIX)
   // For dynamic loading support, NaCl requires a file descriptor on an
   // anonymous file that can have PROT_EXEC applied to its mappings.
-  // Rather than requiring an extra IPC round trip out of the sandbox, we
-  // create an FD here.  Note we're using nacl::CreateMemoryObject rather
-  // than base::SharedMemory here, because the former has code to handle
-  // the Linux cases where shm_open yields objects that do not support
-  // PROT_EXEC mappings.
-  nacl::Handle fd = nacl::CreateMemoryObject(1, true);  // size, executable
-  if (fd == nacl::kInvalidHandle) {
+  // Rather than requiring an extra IPC round trip out of the sandbox,
+  // we create an FD here.
+  base::SharedMemory memory_buffer;
+  if (!memory_buffer.CreateAnonymous(/* size= */ 1)) {
     LOG(ERROR) << "Failed to allocate memory buffer";
     delete this;
     return;
   }
-  nacl::FileDescriptor memory_fd(fd, true);
+  nacl::FileDescriptor memory_fd;
+  memory_fd.fd = dup(memory_buffer.handle().fd);
+  if (memory_fd.fd < 0) {
+    LOG(ERROR) << "Failed to dup() a file descriptor";
+    delete this;
+    return;
+  }
+  memory_fd.auto_close = true;
   handles_for_sel_ldr.push_back(memory_fd);
 #endif