Fix PPB_MouseLock.LockMouse crash and add tests.

ppapi/ppapi_sources.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': {
     'c_source_files': [
       'c/pp_array_output.h',
       'c/pp_bool.h',
       'c/pp_completion_callback.h',
@@ skipping 341 matching lines @@
       'tests/test_image_data.cc',
       'tests/test_image_data.h',
       'tests/test_ime_input_event.cc',
       'tests/test_ime_input_event.h',
       'tests/test_input_event.cc',
       'tests/test_input_event.h',
       'tests/test_memory.cc',
       'tests/test_memory.h',
       'tests/test_mouse_cursor.cc',
       'tests/test_mouse_cursor.h',
+      'tests/test_mouse_lock.cc',
+      'tests/test_mouse_lock.h',
       'tests/test_net_address_private_untrusted.cc',
       'tests/test_net_address_private_untrusted.h',
       'tests/test_paint_aggregator.cc',
       'tests/test_paint_aggregator.h',
       'tests/test_post_message.cc',
       'tests/test_post_message.h',
       'tests/test_scrollbar.cc',
       'tests/test_scrollbar.h',
       'tests/test_tcp_server_socket_private.cc',
       'tests/test_tcp_server_socket_private.h',
@@ skipping 81 matching lines @@
       'tests/test_x509_certificate_private.h',
 
       # Deprecated test cases.
       'tests/test_instance_deprecated.cc',
       'tests/test_instance_deprecated.h',
       'tests/test_var_deprecated.cc',
       'tests/test_var_deprecated.h',
     ],
   },
 }