Restructure the events target into two components:

ui/events/events_base_export.h

Index: ui/events/events_base_export.h
diff --git a/ui/events/events_base_export.h b/ui/events/events_base_export.h
new file mode 100644
index 0000000000000000000000000000000000000000..2da4f78b22483688b2e712d24f5ff679e4f899d6
--- /dev/null
+++ b/ui/events/events_base_export.h
@@ -0,0 +1,29 @@
+// 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 UI_EVENTS_EVENTS_BASE_EXPORT_H_
+#define UI_EVENTS_EVENTS_BASE_EXPORT_H_
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(EVENTS_BASE_IMPLEMENTATION)
+#define EVENTS_BASE_EXPORT __declspec(dllexport)
+#else
+#define EVENTS_BASE_EXPORT __declspec(dllimport)
+#endif  // defined(EVENTS_BASE_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#if defined(EVENTS_BASE_IMPLEMENTATION)
+#define EVENTS_BASE_EXPORT __attribute__((visibility("default")))
+#else
+#define EVENTS_BASE_EXPORT
+#endif
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define EVENTS_BASE_EXPORT
+#endif
+
+#endif  // UI_EVENTS_EVENTS_BASE_EXPORT_H_