Add a new file descriptor watch API.

base/BUILD.gn

 # Copyright (c) 2013 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.
 
 # HOW TO WRITE CONDITIONALS IN THIS FILE
 # ======================================
 #
 # In many other places, one would write a conditional that expresses all the
 # cases when a source file is used or unused, and then either add or subtract
 # it from the sources list in that case
@@ skipping 298 matching lines @@
     "file_descriptor_posix.h",
     "file_version_info.h",
     "file_version_info_mac.h",
     "file_version_info_mac.mm",
     "file_version_info_win.cc",
     "file_version_info_win.h",
     "files/dir_reader_fallback.h",
     "files/dir_reader_linux.h",
     "files/dir_reader_posix.h",
     "files/file.cc",
+    "files/file_descriptor_watcher_posix.cc",
+    "files/file_descriptor_watcher_posix.h",
     "files/file_enumerator.cc",
     "files/file_enumerator.h",
     "files/file_enumerator_posix.cc",
     "files/file_enumerator_win.cc",
     "files/file_path.cc",
     "files/file_path.h",
     "files/file_path_constants.cc",
     "files/file_path_watcher.cc",
     "files/file_path_watcher.h",
     "files/file_path_watcher_fsevents.cc",
@@ skipping 787 matching lines @@
       "threading/platform_thread_linux.cc",
     ]
     set_sources_assignment_filter(sources_assignment_filter)
 
     sources -= [
       "cpu.cc",
       "debug/crash_logging.cc",
       "debug/crash_logging.h",
       "debug/stack_trace.cc",
       "debug/stack_trace_posix.cc",
+      "files/file_descriptor_watcher_posix.cc",
+      "files/file_descriptor_watcher_posix.h",
       "files/file_enumerator_posix.cc",
       "files/file_proxy.cc",
       "files/file_util_proxy.cc",
       "files/important_file_writer.cc",
       "files/important_file_writer.h",
       "files/scoped_temp_dir.cc",
       "memory/discardable_memory.cc",
       "memory/discardable_memory.h",
       "memory/discardable_memory_allocator.cc",
       "memory/discardable_memory_allocator.h",
@@ skipping 638 matching lines @@
     "debug/leak_tracker_unittest.cc",
     "debug/proc_maps_linux_unittest.cc",
     "debug/scoped_thread_heap_usage_unittest.cc",
     "debug/stack_trace_unittest.cc",
     "debug/task_annotator_unittest.cc",
     "deferred_sequenced_task_runner_unittest.cc",
     "environment_unittest.cc",
     "feature_list_unittest.cc",
     "file_version_info_win_unittest.cc",
     "files/dir_reader_posix_unittest.cc",
+    "files/file_descriptor_watcher_posix_unittest.cc",
     "files/file_locking_unittest.cc",
     "files/file_path_unittest.cc",
     "files/file_path_watcher_unittest.cc",
     "files/file_proxy_unittest.cc",
     "files/file_unittest.cc",
     "files/file_util_proxy_unittest.cc",
     "files/file_util_unittest.cc",
     "files/important_file_writer_unittest.cc",
     "files/memory_mapped_file_unittest.cc",
     "files/scoped_temp_dir_unittest.cc",
@@ skipping 653 matching lines @@
     testonly = true
     deps = [
       ":base_java",
     ]
     java_files = [
       "test/android/java/src/org/chromium/base/ContentUriTestUtils.java",
       "test/android/java/src/org/chromium/base/TestSystemMessageHandler.java",
     ]
   }
 }