Relanding r180433, now without build/some.gyp.

remoting/host/host_export.h

Index: remoting/host/host_export.h
diff --git a/remoting/host/host_export.h b/remoting/host/host_export.h
new file mode 100644
index 0000000000000000000000000000000000000000..7aa58d802c05531dd3f4acb40862f64c49dab807
--- /dev/null
+++ b/remoting/host/host_export.h
@@ -0,0 +1,24 @@
+// Copyright (c) 2013 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 REMOTING_HOST_HOST_EXPORT_H_
+#define REMOTING_HOST_HOST_EXPORT_H_
+
+#if defined(WIN32)
+
+#if defined(HOST_IMPLEMENTATION)
+#define HOST_EXPORT __declspec(dllexport)
+#else
+#define HOST_EXPORT __declspec(dllimport)
+#endif  // defined(HOST_IMPLEMENTATION)
+
+#else  // !defined(WIN32)
+#if defined(HOST_IMPLEMENTATION)
+#define HOST_EXPORT __attribute__((visibility("default")))
+#else
+#define HOST_EXPORT
+#endif  // defined(HOST_IMPLEMENTATION)
+#endif  // !defined(WIN32)
+
+#endif  // REMOTING_HOST_HOST_EXPORT_H_