Add base_unittests to win8 trybot. Fix PEImage tests.

base/base_unittests.isolate

 # 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.
 {
   'conditions': [
     ['OS=="android" or OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'files': [
           'test/data/',
         ],
@@ skipping 54 matching lines @@
         ],
       },
     }],
     ['OS=="win" and (fastbuild==0 or fastbuild==1)', {
       'variables': {
         'files': [
           '<(PRODUCT_DIR)/base_unittests.exe.pdb',
         ],
       },
     }],
+    ['OS=="win"', {
+      'variables': {
+        'files': [
+          '<(PRODUCT_DIR)/pe_image_test.dll',
+        ],
+      },
+    }],
   ],
   'includes': [
     'base.isolate',
   ],
 }