mini_installer code cleanups (no functional changes).

chrome/installer/mini_installer.gyp

 {
   'variables': {
     'version_py': '<(DEPTH)/build/util/version.py',
     'version_path': '../../chrome/VERSION',
     'lastchange_path': '<(DEPTH)/build/util/LASTCHANGE',
     # 'branding_dir' is set in the 'conditions' section at the bottom.
     'msvs_use_common_release': 0,
     'msvs_use_common_linker_extras': 0,
     'mini_installer_internal_deps%': 0,
     'mini_installer_official_deps%': 0,
@@ skipping 21 matching lines @@
             '<(SHARED_INTERMEDIATE_DIR)/chrome',
           ],
           'sources': [
             'mini_installer/appid.h',
             'mini_installer/chrome.release',
             'mini_installer/chrome_appid.cc',
             'mini_installer/configuration.cc',
             'mini_installer/configuration.h',
             'mini_installer/decompress.cc',
             'mini_installer/decompress.h',
+            'mini_installer/exit_code.h',
             'mini_installer/mini_installer.cc',
-            'mini_installer/mini_installer.h',
             'mini_installer/mini_installer.ico',
             'mini_installer/mini_installer.rc',
+            'mini_installer/mini_installer_constants.cc',
+            'mini_installer/mini_installer_constants.h',
             'mini_installer/mini_installer_exe_version.rc.version',
             'mini_installer/mini_installer_resource.h',
             'mini_installer/mini_string.cc',
             'mini_installer/mini_string.h',
             'mini_installer/pe_resource.cc',
             'mini_installer/pe_resource.h',
             '<(INTERMEDIATE_DIR)/packed_files.rc',
           ],
           'msvs_settings': {
             'VCCLCompilerTool': {
@@ skipping 252 matching lines @@
       'variables': {
          'branding_dir': '../app/theme/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': '../app/theme/chromium',
       },
     }],
   ],
 }