Allow Mach shm to be passed to NaCl.

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 2f3eefcae5d8c721f5bb3f351f7da5e43313c544..6b187b65169dd3befe068a3d07f2964ea57b3bdb 100644
--- a/components/nacl/loader/nacl_ipc_adapter.cc
+++ b/components/nacl/loader/nacl_ipc_adapter.cc
@@ -543,13 +543,28 @@ bool NaClIPCAdapter::RewriteMessage(const IPC::Message& msg, uint32_t type) {
         case ppapi::proxy::SerializedHandle::SHARED_MEMORY: {
           const base::SharedMemoryHandle& shm_handle = iter->shmem();

[Mark Seaborn, 2015/11/20 18:55:54]

For readability, how about splitting out this conversion into a function like
this one? --

NaClDescWrapper MakeShmNaClDesc(const base::SharedMemoryHandle& handle, uint32_t
size);

[erikchen, 2015/11/20 21:51:12]

Done.

           uint32_t size = iter->size();
+#if defined(OS_MACOSX) && !defined(OS_IOS)

[Mark Seaborn, 2015/11/20 18:55:54]

This file shouldn't be getting compiled for iOS.  It would be better to omit the
check for iOS so as not to mislead readers about what this code supports.

[erikchen, 2015/11/20 21:51:12]

Done.

+          switch (shm_handle.GetType()) {
+            case base::SharedMemoryHandle::MACH:
+              nacl_desc.reset(new NaClDescWrapper(NaClDescImcShmMachMake(
+                  shm_handle.GetMemoryObject(),
+                  static_cast<size_t>(size))));
+              break;
+            case base::SharedMemoryHandle::POSIX:
+              nacl_desc.reset(new NaClDescWrapper(NaClDescImcShmMake(

[Mark Seaborn, 2015/11/20 18:55:54]

This is the same as the code in the #else, so you could reduce duplication with:

#if defined(OS_MACOSX)
if (shm_handle.GetType() == base::SharedMemoryHandle::MACH) {
  return new NaClDescWrapper(...);
}
CHECK_EQ(shm_handle.GetType(), base::SharedMemoryHandle::POSIX);
#endif
// Generic case...

[erikchen, 2015/11/20 21:51:12]

Done.

+                  base::SharedMemory::GetFdFromSharedMemoryHandle(shm_handle),
+                  static_cast<size_t>(size))));
+              break;
+          }
+#else
           nacl_desc.reset(new NaClDescWrapper(NaClDescImcShmMake(
 #if defined(OS_WIN)
               shm_handle.GetHandle(),
 #else
               base::SharedMemory::GetFdFromSharedMemoryHandle(shm_handle),
-#endif
+#endif  // defined(OS_WIN)
               static_cast<size_t>(size))));
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
           break;
         }
         case ppapi::proxy::SerializedHandle::SOCKET: {