Extract //device/usb mocks so that they can be shared.

extensions/extensions_tests.gyp

 {
   'includes': [
     'extensions_tests.gypi',
   ],
   'variables': {
     # Product name is used for Mac bundle.
     'app_shell_product_name': 'App Shell',
     # The version is high enough to be supported by Omaha (at least 31)
     # but fake enough to be obviously not a Chrome release.
     'app_shell_version': '38.1234.5678.9',
@@ skipping 60 matching lines @@
         'extensions.gyp:extensions_test_support',
         'shell/app_shell.gyp:app_shell_lib',
         # TODO(yoz): find the right deps
         '<(DEPTH)/base/base.gyp:test_support_base',
         '<(DEPTH)/components/components.gyp:guest_view',
         '<(DEPTH)/components/components.gyp:guest_view_test_support',
         '<(DEPTH)/content/content.gyp:content_app_both',
         '<(DEPTH)/content/content_shell_and_tests.gyp:content_browser_test_support',
         '<(DEPTH)/content/content_shell_and_tests.gyp:test_support_content',
         '<(DEPTH)/device/bluetooth/bluetooth.gyp:device_bluetooth_mocks',
+        '<(DEPTH)/device/usb/usb.gyp:device_usb_mocks',
         '<(DEPTH)/testing/gmock.gyp:gmock',
         '<(DEPTH)/testing/gtest.gyp:gtest',
       ],
       'defines': [
         'HAS_OUT_OF_PROC_TEST_RUNNER',
       ],
       'sources': [
         '<@(extensions_browsertests_sources)',
       ],
       'conditions': [
@@ skipping 30 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'extensions_browsertests.isolate',
           ],
         },
       ],
     }],
   ],
 }