Add the pdf plugin's source in src\pdf.

build/all.gyp

 # 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': {
     # A hook that can be overridden in other repositories to add additional
     # compilation targets to 'All'. Only used on Android.
     'android_app_targets%': [],
   },
@@ skipping 1085 matching lines @@
                 '../chrome/chrome.gyp:crash_service',
                 '../chrome/chrome.gyp:gcapi_dll',
                 '../chrome/chrome.gyp:pack_policy_templates',
                 '../chrome/installer/mini_installer.gyp:mini_installer',
                 '../cloud_print/cloud_print.gyp:cloud_print',
                 '../courgette/courgette.gyp:courgette',
                 '../courgette/courgette.gyp:courgette64',
                 '../ipc/ipc.gyp:ipc_tests',
                 '../media/media.gyp:media_unittests',
                 '../net/net.gyp:net_unittests_run',
+                '../pdf/pdf.gyp:pdf',
                 '../printing/printing.gyp:printing_unittests',
                 '../remoting/remoting.gyp:remoting_webapp',
                 '../sql/sql.gyp:sql_unittests',
                 '../sync/sync.gyp:sync_unit_tests',
                 '../third_party/widevine/cdm/widevine_cdm.gyp:widevinecdmadapter',
                 '../ui/gfx/gfx.gyp:gfx_unittests',
                 '../ui/ui_unittests.gyp:ui_unittests',
                 '../ui/views/views.gyp:views_unittests',
                 '../url/url.gyp:url_unittests',
               ],
               'conditions': [
-                ['internal_pdf', {
-                  'dependencies': [
-                    '../pdf/pdf.gyp:pdf',
-                  ],
-                }], # internal_pdf
                 ['target_arch=="ia32"', {
                   'dependencies': [
                     '../chrome/chrome.gyp:crash_service_win64',
                   ],
                 }],
                 ['component != "shared_library" and wix_exists == "True" and \
                     sas_dll_exists == "True"', {
                   'dependencies': [
                     '../remoting/remoting.gyp:remoting_host_installation',
                   ],
@@ skipping 106 matching lines @@
             # http://crbug.com/157234
             #'../chrome/chrome.gyp:sync_integration_tests_run',
             '../chrome/chrome.gyp:unit_tests_run',
             '../net/net.gyp:net_unittests_run',
           ],
         }, # target_name: chromium_swarm_tests
       ],
     }],
   ], # conditions
 }