Mojo: add support for disallowing sync calls for a process.

mojo/edk/embedder/embedder.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_EDK_EMBEDDER_EMBEDDER_H_
 #define MOJO_EDK_EMBEDDER_EMBEDDER_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 171 matching lines @@
 // have this token and call CreateParentMessagePipe() with it in order for the
 // pipe to get connected.
 MOJO_SYSTEM_IMPL_EXPORT ScopedMessagePipeHandle
 CreateChildMessagePipe(const std::string& token);
 
 // Generates a random ASCII token string for use with CreateParentMessagePipe()
 // and CreateChildMessagePipe() above. The generated token is suitably random so
 // as to not have to worry about collisions with other generated tokens.
 MOJO_SYSTEM_IMPL_EXPORT std::string GenerateRandomToken();
 
+// Sets system properties that can be read by the MojoGetProperty() API. See the
+// documentation for MojoPropertyType for supported property types and their
+// corresponding value type.
+//
+// Default property values:
+//   |MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED| - true
+MOJO_SYSTEM_IMPL_EXPORT MojoResult SetProperty(MojoPropertyType type,
+                                               const void* value);
+
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_EMBEDDER_EMBEDDER_H_