Add stubs for brailleDisplayPrivate extension API.

chrome/common/extensions/api/braille_display_private.idl

+// Copyright (c) 2012 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.
+
+// Braille display access private API.
+namespace brailleDisplayPrivate {
+  // Braille display keyboard command.
+  enum KeyCommand {
+    line_up,
+    line_down,
+    pan_left,
+    pan_right,
+    top,
+    bottom,
+    routing,
+    secondary_routing,
+    dots,
+    standard_key
+  };
+
+  // A keyboard event.  This is not a standard keyboard event because
+  // braille display keyboards look significantly different from standard
+  // keyboards.
+  dictionary KeyEvent {
+    KeyCommand command;
+    // 0-based display position for commands that involve a routing key.
+    long? displayPosition;
+    // Braille dot keys that were pressed, stored in the low-order bits.
+    // Dot 1 is stored in bit 0, dot2 in bit 1, etc.
+    long? brailleDots;
+    // DOM keyboard event for a key that corresponds to a standard key.
+    DOMString? standardKeyName;
+    // Whether the space key was pressed.
+    boolean? spaceKey;
+    // Whether the alt key was pressed.
+    boolean? altKey;
+    // Whether the shift key was pressed.
+    boolean? shiftKey;
+    // Whether the ctrl key was pressed.
+    boolean? ctrlKey;
+  };
+
+  // The current braille display state.
+  dictionary DisplayState {
+    // Whether a braille display is currently available.
+    boolean available;
+    // Number of braille cells on the currently connected display.
+    long? textCellCount;
+  };
+
+  callback DisplayStateCallback = void(DisplayState result);
+
+  interface Functions {
+    // Gets the current display state.
+    static void getDisplayState(DisplayStateCallback callback);
+    // Write the given dot patterns to the display.  The buffer contains one
+    // byte for each braille cell on the display, starting from the leftmost
+    // cell. Each byte contains a bit pattern indicating which dots should be
+    // raised in the corresponding cell with the low-order bit representing
+    // dot 1 and so on until bit 7 which corresponds to dot 8.  If the number
+    // of bytes in the buffer is not equal to the display size, the buffer
+    // will either be clipped or padded with blank cells on the right.
+    static void writeDots(ArrayBuffer cells);
+  };
+
+  interface Events {
+    // Fired when a braille display is connected or disconnected.
+    static void onDisplayStateChanged(DisplayState state);
+    // Fired when an input event is received from the display.
+    static void onKeyEvent(KeyEvent event);
+  };
+};