Adding the option to drop in a new BrowserDistribution instance for experimen...

chrome/installer/installer.gyp

 {
   'variables': {
     'version_py': '../../chrome/tools/build/version.py',
     'version_path': '../../chrome/VERSION',
     'lastchange_path': '<(SHARED_INTERMEDIATE_DIR)/build/LASTCHANGE',
     # 'branding_dir' is set in the 'conditions' section at the bottom.
   },
   'includes': [
     '../../build/common.gypi',
   ],
@@ skipping 13 matching lines @@
             '../../courgette/courgette.gyp:courgette_lib',
             '../../third_party/bspatch/bspatch.gyp:bspatch',
             '../../third_party/icu/icu.gyp:icui18n',
             '../../third_party/icu/icu.gyp:icuuc',
             '../../third_party/libxml/libxml.gyp:libxml',
             '../../third_party/lzma_sdk/lzma_sdk.gyp:lzma_sdk',
           ],
           'include_dirs': [
             '../..',
           ],
+          'variables': {
+            'extra_installer_util_sources%': [
+            ],
+          },
           'sources': [
             'util/browser_distribution.cc',
             'util/browser_distribution.h',
             'util/compat_checks.cc',
             'util/compat_checks.h',
             'util/copy_tree_work_item.cc',
             'util/copy_tree_work_item.h',
             'util/create_dir_work_item.cc',
             'util/create_dir_work_item.h',
             'util/create_reg_key_work_item.cc',
@@ skipping 33 matching lines @@
             'util/util_constants.cc',
             'util/util_constants.h',
             'util/version.cc',
             'util/version.h',
             'util/work_item.cc',
             'util/work_item.h',
             'util/work_item_list.cc',
             'util/work_item_list.h',
             '../common/json_value_serializer.cc',
             '../common/pref_names.cc',
+            '<@(extra_installer_util_sources)',
           ],
         },
         {
           'target_name': 'gcapi_dll',
           'type': 'loadable_module',
           'msvs_guid': 'B802A2FE-E4E2-4F5A-905A-D5128875C954',
           'dependencies': [
             '../../google_update/google_update.gyp:google_update',
           ],
           'include_dirs': [
@@ skipping 521 matching lines @@
       'variables': {
          'branding_dir': '../app/theme/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': '../app/theme/chromium',
       },
     }],
   ],
 }