NaCl: create a separate namespace for Mojo handles.

mojo/edk/system/core.cc

Index: mojo/edk/system/core.cc
diff --git a/mojo/edk/system/core.cc b/mojo/edk/system/core.cc
index 80c3d367ba16858731d2c0527c4c073a7faee245..cde236ce19cd3ee770928685757d4feececd3385 100644
--- a/mojo/edk/system/core.cc
+++ b/mojo/edk/system/core.cc
@@ -97,6 +97,21 @@ scoped_refptr<Dispatcher> Core::GetDispatcher(MojoHandle handle) {
   return handle_table_.GetDispatcher(handle);
 }
 
+scoped_refptr<Dispatcher> Core::PopDispatcher(MojoHandle handle) {
+  if (handle == MOJO_HANDLE_INVALID)
+    return nullptr;
+
+  scoped_refptr<Dispatcher> dispatcher;
+  {
+    base::AutoLock locker(handle_table_lock_);
+    MojoResult result =
+        handle_table_.GetAndRemoveDispatcher(handle, &dispatcher);
+    if (result != MOJO_RESULT_OK)
+      return nullptr;
+  }
+  return dispatcher;
+}
+
 MojoResult Core::AsyncWait(MojoHandle handle,
                            MojoHandleSignals signals,
                            const base::Callback<void(MojoResult)>& callback) {