Add ChromeVox panel and implement caption display functionality.

chrome/chrome_browser_chromeos.gypi

 # 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.
 
 {
   'variables': {
     # These files lists are shared with the GN build.
     'browser_chromeos_sources': [
         # All .cc, .h, .m, and .mm files under browser/chromeos, except for tests
         # and mocks.
         'browser/chromeos/accessibility/accessibility_manager.cc',
         'browser/chromeos/accessibility/accessibility_manager.h',
         'browser/chromeos/accessibility/accessibility_util.cc',
         'browser/chromeos/accessibility/accessibility_util.h',
+        'browser/chromeos/accessibility/chromevox_panel.cc',
+        'browser/chromeos/accessibility/chromevox_panel.h',
         'browser/chromeos/accessibility/magnification_manager.cc',
         'browser/chromeos/accessibility/magnification_manager.h',
         'browser/chromeos/accessibility/spoken_feedback_event_rewriter.cc',
         'browser/chromeos/accessibility/spoken_feedback_event_rewriter.h',
         'browser/chromeos/app_mode/app_launch_utils.cc',
         'browser/chromeos/app_mode/app_launch_utils.h',
         'browser/chromeos/app_mode/app_session_lifetime.cc',
         'browser/chromeos/app_mode/app_session_lifetime.h',
         'browser/chromeos/app_mode/certificate_manager_dialog.cc',
         'browser/chromeos/app_mode/certificate_manager_dialog.h',
@@ skipping 1309 matching lines @@
         'browser/chromeos/attestation/attestation_signed_data.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/chromeos/attestation',
         'proto_out_dir': 'chrome/browser/chromeos/attestation',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }