Move scoped_observer.h from base_unittests to base. It is not a test.

base/base.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': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/win_precompile.gypi',
@@ skipping 540 matching lines @@
         'process/memory_unittest_mac.mm',
         'process/process_metrics_unittest.cc',
         'process/process_metrics_unittest_ios.cc',
         'process/process_util_unittest.cc',
         'profiler/tracked_time_unittest.cc',
         'rand_util_unittest.cc',
         'numerics/safe_numerics_unittest.cc',
         'scoped_clear_errno_unittest.cc',
         'scoped_generic_unittest.cc',
         'scoped_native_library_unittest.cc',
-        'scoped_observer.h',
         'security_unittest.cc',
         'sequence_checker_unittest.cc',
         'sha1_unittest.cc',
         'stl_util_unittest.cc',
         'strings/nullable_string16_unittest.cc',
         'strings/safe_sprintf_unittest.cc',
         'strings/string16_unittest.cc',
         'strings/stringprintf_unittest.cc',
         'strings/string_number_conversions_unittest.cc',
         'strings/string_piece_unittest.cc',
@@ skipping 929 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }