Add memory pressure monitor for Linux.

components/components_tests.gyp

 # Copyright 2014 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 turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 323 matching lines @@
     'language_usage_metrics_unittest_sources': [
       'language_usage_metrics/language_usage_metrics_unittest.cc',
     ],
     'leveldb_proto_unittest_sources': [
       'leveldb_proto/proto_database_impl_unittest.cc',
     ],
     'login_unittest_sources': [
       'login/screens/screen_context_unittest.cc',
     ],
     'memory_pressure_unittest_sources': [
+      'memory_pressure/direct_memory_pressure_calculator_linux_unittest.cc',
       'memory_pressure/direct_memory_pressure_calculator_win_unittest.cc',
       'memory_pressure/filtered_memory_pressure_calculator_unittest.cc',
       'memory_pressure/memory_pressure_stats_collector_unittest.cc',
       'memory_pressure/test_memory_pressure_calculator.cc',
       'memory_pressure/test_memory_pressure_calculator.h',
     ],
     'metrics_unittest_sources': [
       'metrics/call_stack_profile_metrics_provider_unittest.cc',
       'metrics/cloned_install_detector_unittest.cc',
       'metrics/daily_event_unittest.cc',
@@ skipping 1533 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }