Use standardized and extendable accelerometer update type.

ui/accelerometer/ui_accelerometer_export.h

Index: ui/accelerometer/ui_accelerometer_export.h
diff --git a/ui/accelerometer/ui_accelerometer_export.h b/ui/accelerometer/ui_accelerometer_export.h
new file mode 100644
index 0000000000000000000000000000000000000000..97727f5ff454e7dc2e40613d7f3892d4b0ad5f95
--- /dev/null
+++ b/ui/accelerometer/ui_accelerometer_export.h
@@ -0,0 +1,37 @@
+// 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 UI_ACCELEROMETER_UI_ACCELEROMETER_EXPORT_H_
+#define UI_ACCELEROMETER_UI_ACCELEROMETER_EXPORT_H_
+
+// Defines UI_ACCELEROMETER_EXPORT so that functionality implemented by the UI
+// accelerometer module can be exported to consumers.
+
+#if defined(COMPONENT_BUILD)
+
+#if defined(WIN32)
+
+#if defined(UI_ACCELEROMETER_IMPLEMENTATION)
+#define UI_ACCELEROMETER_EXPORT __declspec(dllexport)
+#else
+#define UI_ACCELEROMETER_EXPORT __declspec(dllimport)
+#endif
+
+#else  // !defined(WIN32)
+
+#if defined(UI_ACCELEROMETER_IMPLEMENTATION)
+#define UI_ACCELEROMETER_EXPORT __attribute__((visibility("default")))
+#else
+#define UI_ACCELEROMETER_EXPORT
+#endif
+
+#endif
+
+#else  // !defined(COMPONENT_BUILD)
+
+#define UI_ACCELEROMETER_EXPORT
+
+#endif
+
+#endif  // UI_ACCELEROMETER_UI_ACCELEROMETER_EXPORT_H_