Revert 106677 (caused several PPAPI test timeouts, see http://crbug.com/101154)

ppapi/ppapi_proxy.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'ppapi_proxy',
       'type': '<(component)',
       'dependencies': [
         '../base/base.gyp:base',
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '../gpu/gpu.gyp:gpu_ipc',
         '../ipc/ipc.gyp:ipc',
         '../skia/skia.gyp:skia',
         '../ui/gfx/surface/surface.gyp:surface',
         'ppapi.gyp:ppapi_c',
         'ppapi_shared',
       ],
       'all_dependent_settings': {
         'include_dirs': [
            '..',
         ],
       },
       'include_dirs': [
         '..',
         '../..',  # For nacl includes to work.
       ],
       'sources': [
+        'proxy/callback_tracker.cc',
+        'proxy/callback_tracker.h',
         'proxy/broker_dispatcher.cc',
         'proxy/broker_dispatcher.h',
         'proxy/dispatcher.cc',
         'proxy/dispatcher.h',
         'proxy/enter_proxy.h',
         'proxy/host_dispatcher.cc',
         'proxy/host_dispatcher.h',
         'proxy/host_var_serialization_rules.cc',
         'proxy/host_var_serialization_rules.h',
         'proxy/interface_list.cc',
@@ skipping 109 matching lines @@
         'proxy/serialized_var.cc',
         'proxy/serialized_var.h',
         'proxy/var_serialization_rules.h',
       ],
       'defines': [
         'PPAPI_PROXY_IMPLEMENTATION',
       ],
     },
   ],
 }