Compile FileCache related files only on Chrome OS.

chrome/chrome_tests_unit.gypi

 # Copyright 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': {
     'chrome_unit_tests_sources': [
       # histograms.xml is analyzed by AboutFlagsHistogramTest, so this
       # dependency is needed to make commit bots run unit_tests on
       # histograms.xml changes.
       '../tools/metrics/histograms/histograms.xml',
@@ skipping 2532 matching lines @@
         }],
         ['chromeos==1', {
           'sources': [
             '<@(chrome_unit_tests_chromeos_sources)',
             '<@(chrome_unit_tests_chromeos_gtestjs_sources)',
             '<@(chrome_unit_tests_chromeos_js_sources)',
           ],
           'dependencies': [
             '../ash/ash_resources.gyp:ash_resources',
             '../components/components.gyp:drive_test_support',
+            '../components/components.gyp:drive_test_support_chromeos',
             '../ui/chromeos/ui_chromeos.gyp:ui_chromeos_resources',
           ],
           'sources!': [
             'browser/signin/signin_manager_unittest.cc',
             'browser/signin/signin_names_io_thread_unittest.cc',
           ],
         }],
         ['use_x11==1', {
           'dependencies': [
             '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
@@ skipping 494 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }