Use ChannelMojo between app shims and the browser process.

mojo/edk/embedder/platform_channel_utils_posix.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_PLATFORM_CHANNEL_UTILS_POSIX_H_
 #define MOJO_EDK_EMBEDDER_PLATFORM_CHANNEL_UTILS_POSIX_H_
 
 #include <stddef.h>
 #include <sys/types.h>  // For |ssize_t|.
 
@@ skipping 57 matching lines @@
 PlatformChannelRecvmsg(PlatformHandle h,
                        void* buf,
                        size_t num_bytes,
                        std::deque<PlatformHandle>* platform_handles,
                        bool block = false);
 
 // Returns false if |server_handle| encounters an unrecoverable error.
 // Returns true if it's valid to keep listening on |server_handle|. In this
 // case, it's possible that a connection wasn't successfully established; then,
 // |connection_handle| will be invalid.
-bool ServerAcceptConnection(PlatformHandle server_handle,
-                            ScopedPlatformHandle* connection_handle);
+MOJO_SYSTEM_IMPL_EXPORT bool ServerAcceptConnection(
+    PlatformHandle server_handle,
+    ScopedPlatformHandle* connection_handle);
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_EMBEDDER_PLATFORM_CHANNEL_UTILS_POSIX_H_