Add POSIX shared memory support for Mac

components/nacl/loader/nacl_ipc_adapter.cc

Index: components/nacl/loader/nacl_ipc_adapter.cc
diff --git a/components/nacl/loader/nacl_ipc_adapter.cc b/components/nacl/loader/nacl_ipc_adapter.cc
index 3b1110251d1905d6fa2b9aa914dda0a3921d380c..9100ed6fbf99776fd5f1bc24695ce493ce82d993 100644
--- a/components/nacl/loader/nacl_ipc_adapter.cc
+++ b/components/nacl/loader/nacl_ipc_adapter.cc
@@ -234,9 +234,16 @@ std::unique_ptr<NaClDescWrapper> MakeShmNaClDesc(
     const base::SharedMemoryHandle& handle,
     size_t size) {
 #if defined(OS_MACOSX)
-  return std::unique_ptr<NaClDescWrapper>(new NaClDescWrapper(
-      NaClDescImcShmMachMake(handle.GetMemoryObject(), size)));
-#else
+  if (handle.GetType() == base::SharedMemoryHandle::MACH) {
+    return std::unique_ptr<NaClDescWrapper>(new NaClDescWrapper(
+        NaClDescImcShmMachMake(handle.GetMemoryObject(), size)));
+  } else {
+    // We should never pass POSIX shared memory over IPC.
+    CHECK(false);
+    return nullptr;
+  }
+#endif
+
   return std::unique_ptr<NaClDescWrapper>(
       new NaClDescWrapper(NaClDescImcShmMake(
 #if defined(OS_WIN)
@@ -245,7 +252,6 @@ std::unique_ptr<NaClDescWrapper> MakeShmNaClDesc(
           base::SharedMemory::GetFdFromSharedMemoryHandle(handle),
 #endif
           size)));
-#endif
 }
 
 }  // namespace