Moved chrome/common/policy to components/policy.

This change also introduces //components/policy as a new layered component.
Some of the chrome/browser/policy code is being prepared to be moved into this
component.

This CL depends on https://codereview.chromium.org/22807004/.

BUG=271392

Review URL: https://chromiumcodereview.appspot.com/23045003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@217552 0039d316-1c4b-4281-b951-d872f2087c98

diff --git a/components/policy/policy_export.h b/components/policy/policy_export.h
new file mode 100644
index 0000000..47376ac
--- /dev/null
+++ b/components/policy/policy_export.h

@@ -0,0 +1,29 @@
+// Copyright 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 COMPONENTS_POLICY_POLICY_EXPORT_H_
+#define COMPONENTS_POLICY_POLICY_EXPORT_H_
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(POLICY_COMPONENT_IMPLEMENTATION)
+#define POLICY_EXPORT __declspec(dllexport)
+#else
+#define POLICY_EXPORT __declspec(dllimport)
+#endif  // defined(BASE_PREFS_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#if defined(POLICY_COMPONENT_IMPLEMENTATION)
+#define POLICY_EXPORT __attribute__((visibility("default")))
+#else
+#define POLICY_EXPORT
+#endif
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define POLICY_EXPORT
+#endif
+
+#endif  // COMPONENTS_POLICY_POLICY_EXPORT_H_