Make changes to mini_installer test files trigger tests.

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,
   },
   'includes': [
     '../../build/win_precompile.gypi',
   ],
   'conditions': [
     ['OS=="win"', {
+      'includes': [
+        '../test/mini_installer/test_installer.gypi',
+      ],
       'targets': [
         {
+          # A target that is outdated if any of the mini_installer test sources
+          # are modified.
+          'target_name': 'test_installer_sentinel',
+          'type': 'none',
+          'actions': [
+            {
+              'action_name': 'touch_sentinel',
+              'variables': {
+                'touch_sentinel_py': '../tools/build/win/touch_sentinel.py',
+              },
+              'inputs': [
+                '<@(test_installer_sources)',  # from test_installer.gypi
+                '<(touch_sentinel_py)',
+              ],
+              'outputs': ['<(SHARED_INTERMEDIATE_DIR)/chrome/installer/test_installer_sentinel'],
+              'action': ['python', '<(touch_sentinel_py)', '<@(_outputs)'],
+            },
+          ],
+        },
+        {
           'target_name': 'mini_installer',
           'type': 'executable',
 
           'dependencies': [
             '../chrome.gyp:chrome',
             '../chrome.gyp:chrome_nacl_win64',
             '../chrome.gyp:chrome_dll',
             '../chrome.gyp:default_extensions',
             '../chrome.gyp:setup',
+            'test_installer_sentinel',
           ],
           'include_dirs': [
             '../..',
             '<(INTERMEDIATE_DIR)',
             '<(SHARED_INTERMEDIATE_DIR)/chrome',
           ],
           'sources': [
             '<(INTERMEDIATE_DIR)/packed_files.rc',
             'mini_installer/appid.h',
             'mini_installer/chrome.release',
@@ skipping 279 matching lines @@
       'variables': {
          'branding_dir': '../app/theme/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': '../app/theme/chromium',
       },
     }],
   ],
 }