Add PPAPI decryptor implementation.

ppapi/ppapi_proxy.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.
 
 {
   'target_defaults': {
     'variables': {
       'ppapi_proxy_target': 0,
     },
     'target_conditions': [
@@ skipping 106 matching lines @@
           'proxy/ppb_var_deprecated_proxy.cc',
           'proxy/ppb_var_deprecated_proxy.h',
           'proxy/ppb_video_capture_proxy.cc',
           'proxy/ppb_video_capture_proxy.h',
           'proxy/ppb_video_decoder_proxy.cc',
           'proxy/ppb_video_decoder_proxy.h',
           'proxy/ppb_x509_certificate_private_proxy.cc',
           'proxy/ppb_x509_certificate_private_proxy.h',
           'proxy/ppp_class_proxy.cc',
           'proxy/ppp_class_proxy.h',
+          'proxy/ppp_content_decryptor_private_proxy.cc',
+          'proxy/ppp_content_decryptor_private_proxy.h',
           'proxy/ppp_graphics_3d_proxy.cc',
           'proxy/ppp_graphics_3d_proxy.h',
           'proxy/ppp_input_event_proxy.cc',
           'proxy/ppp_input_event_proxy.h',
           'proxy/ppp_instance_private_proxy.cc',
           'proxy/ppp_instance_private_proxy.h',
           'proxy/ppp_instance_proxy.cc',
           'proxy/ppp_instance_proxy.h',
           'proxy/ppp_messaging_proxy.cc',
           'proxy/ppp_messaging_proxy.h',
@@ skipping 58 matching lines @@
               'proxy/ppp_instance_private_proxy.cc',
               'proxy/ppp_video_decoder_proxy.cc',
               'proxy/serialized_flash_menu.cc',
             ],
           }],
         ],
       }],
     ],
   },
 }