Makes the code simpler by automatically deducing the root directory to use.

third_party/cacheinvalidation/cacheinvalidation.gyp

 # 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.
 
 {
   'variables': {
     # This library should build cleanly with the extra warnings turned on
     # for Chromium.
     'chromium_code': 1,
     # The root directory for the proto files.
@@ skipping 214 matching lines @@
             'cacheinvalidation_unittests.isolate',
             '<@(isolate_dependency_tracked)',
           ],
           'outputs': [
             '<(PRODUCT_DIR)/cacheinvalidation_unittests.results',
           ],
           'action': [
             'python',
             '../../tools/isolate/isolate.py',
             '--mode', '<(tests_run)',
-            '--variable', 'DEPTH', '<(DEPTH)',
             '--variable', 'PRODUCT_DIR', '<(PRODUCT_DIR)',
             '--variable', 'OS', '<(OS)',
             '--result', '<@(_outputs)',
             'cacheinvalidation_unittests.isolate',
           ],
         },
       ],
     },
   ],
 }