Restructure the events target into two components:

ui/events/keycodes/keyboard_code_conversion_x.h

 // Copyright (c) 2011 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_KEYCODES_KEYBOARD_CODE_CONVERSION_X_H_
 #define UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_X_H_
 
 #include "base/basictypes.h"
-#include "ui/events/events_export.h"
+#include "ui/events/events_base_export.h"
 #include "ui/events/keycodes/keyboard_codes_posix.h"
 
 typedef union _XEvent XEvent;
 
 namespace ui {
 
-EVENTS_EXPORT KeyboardCode KeyboardCodeFromXKeyEvent(XEvent* xev);
+EVENTS_BASE_EXPORT KeyboardCode KeyboardCodeFromXKeyEvent(XEvent* xev);
 
-EVENTS_EXPORT KeyboardCode KeyboardCodeFromXKeysym(unsigned int keysym);
+EVENTS_BASE_EXPORT KeyboardCode KeyboardCodeFromXKeysym(unsigned int keysym);
 
 // Returns a character on a standard US PC keyboard from an XEvent.
-EVENTS_EXPORT uint16 GetCharacterFromXEvent(XEvent* xev);
+EVENTS_BASE_EXPORT uint16 GetCharacterFromXEvent(XEvent* xev);
 
 // Converts a KeyboardCode into an X KeySym.
-EVENTS_EXPORT int XKeysymForWindowsKeyCode(KeyboardCode keycode, bool shift);
+EVENTS_BASE_EXPORT int XKeysymForWindowsKeyCode(KeyboardCode keycode,
+                                                bool shift);
 
 // Converts an X keycode into an X KeySym.
 unsigned int DefaultXKeysymFromHardwareKeycode(unsigned int keycode);
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_X_H_