Register system Pepper Flash plugin if no packaged Pepper plugin is found.

chrome/common/BUILD.gn

 # Copyright 2014 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.
 
 import("//tools/grit/grit_rule.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("../chrome_common.gypi") ],
                           "scope",
                           [ "../chrome_common.gypi" ])
@@ skipping 190 matching lines @@
     deps += [
       "//third_party/mach_override",
       "//third_party/google_toolbox_for_mac",
     ]
   }
 
   if (enable_plugins) {
     sources += [
       "pepper_flash.cc",
       "pepper_flash.h",
+      "ppapi_utils.cc",
+      "ppapi_utils.h",
     ]
     deps += [ "//third_party/adobe/flash:flapper_version_h" ]
   }
   if (enable_plugins && enable_extensions) {
     sources += [
       "pepper_permission_util.cc",
       "pepper_permission_util.h",
     ]
   }
   if (!enable_webrtc) {
@@ skipping 91 matching lines @@
     ]
   }
 
   if (enable_extensions) {
     sources += [
       "extensions/extension_test_util.cc",
       "extensions/extension_test_util.h",
     ]
   }
 }