Fuchsia port of base/time, with some refactoring of POSIX time modules.

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 906 matching lines @@
     "time/clock.cc",
     "time/clock.h",
     "time/default_clock.cc",
     "time/default_clock.h",
     "time/default_tick_clock.cc",
     "time/default_tick_clock.h",
     "time/tick_clock.cc",
     "time/tick_clock.h",
     "time/time.cc",
     "time/time.h",
-    "time/time_mac.cc",

[Lei Zhang, 2017/05/17 08:34:16]

This has the advantage of the files are mostly listed together and almost never
repeated. Do we want to keep it like this, let the default
sources_assignment_filter rules in build/config/BUILDCONFIG.gn do their thing,
and tweak the sources afterwards?

i.e.
1) List everything here.
2) Exclude time_exploded_posix.cc and time_now_posix.cc just below line 1468.
3) Add a new conditional rule to exclude time_now_posix.cc for Fuchsia.

[miu, 2017/05/18 02:52:38]

I was discussing this with thakis@ at on the code review that added the Fuchsia
build config. The advice I got there was that we want to remove the use of
sources_assignment_filter in the long-term, and instead explicitly "source +=
[...]" files for each platform. To be fair, I'm not sure if there was an
official decision on this, but scottmg@ agreed and also mentioned Brett had made
similar comments.

If you're curious, here's the discussion on that:
https://codereview.chromium.org/2784063002/#msg54

Also, FWIW, the top of this particular BUILD.gn file has a related comment, that
states we should prefer to mention files in more than one list so that it's more
clear under which conditions it will be built.

Sound good to you, to leave it as I have it now?

[Lei Zhang, 2017/05/18 19:06:12]

I've always found the sources_assignment_filter to be convinent. Oftentimes, but
not always, it does the right thing. But sure, let's leave this as is, given the
comments at the top of the file.

-    "time/time_posix.cc",
-    "time/time_win.cc",
     "timer/elapsed_timer.cc",
     "timer/elapsed_timer.h",
     "timer/hi_res_timer_manager.h",
     "timer/hi_res_timer_manager_posix.cc",
     "timer/hi_res_timer_manager_win.cc",
     "timer/mock_timer.cc",
     "timer/mock_timer.h",
     "timer/timer.cc",
     "timer/timer.h",
     "trace_event/auto_open_close_event.cc",
@@ skipping 398 matching lines @@
       ]
     }
   }
 
   # Windows.
   if (is_win) {
     sources += [
       "power_monitor/power_monitor_device_source_win.cc",
       "profiler/win32_stack_frame_unwinder.cc",
       "profiler/win32_stack_frame_unwinder.h",
+      "time/time_win.cc",
     ]
 
     sources -= [
       "file_descriptor_store.cc",
       "file_descriptor_store.h",
       "memory/shared_memory_helper.cc",
       "memory/shared_memory_helper.h",
       "message_loop/message_pump_libevent.cc",
       "strings/string16.cc",
     ]
@@ skipping 87 matching lines @@
   } else if (!is_nacl || is_nacl_nonsfi) {
     # Non-Windows.
     deps += [ "//base/third_party/libevent" ]
   }
 
   # Desktop Mac.
   if (is_mac) {
     sources += [
       "mac/scoped_typeref.h",
       "power_monitor/power_monitor_device_source_mac.mm",
+      "time/time_conversion_posix.cc",
+      "time/time_mac.cc",
     ]
 
     libs = [
       "ApplicationServices.framework",
       "AppKit.framework",
       "bsm",
       "CoreFoundation.framework",
       "IOKit.framework",
       "Security.framework",
     ]
@@ skipping 125 matching lines @@
       "mac/scoped_objc_class_swizzler.h",
       "mac/scoped_objc_class_swizzler.mm",
       "mac/scoped_typeref.h",
       "memory/shared_memory_posix.cc",
       "message_loop/message_pump_mac.h",
       "message_loop/message_pump_mac.mm",
       "power_monitor/power_monitor_device_source_ios.mm",
       "process/memory_stubs.cc",
       "strings/sys_string_conversions_mac.mm",
       "threading/platform_thread_mac.mm",
+      "time/time_conversion_posix.cc",
       "time/time_mac.cc",
     ]
 
     set_sources_assignment_filter(sources_assignment_filter)
   }
 
+  # Fuchsia.
+  if (is_fuchsia) {
+    sources += [
+      "time/time_conversion_posix.cc",
+      "time/time_exploded_posix.cc",
+      "time/time_fuchsia.cc",
+    ]
+  }
+
+  if (is_posix && !is_fuchsia && !is_mac && !is_ios) {
+    sources += [
+      "time/time_conversion_posix.cc",
+      "time/time_exploded_posix.cc",
+      "time/time_now_posix.cc",
+    ]
+  }
+
   if (is_posix && !is_mac && !is_ios && !is_android && !is_chromeos) {
     sources += [ "power_monitor/power_monitor_device_source_posix.cc" ]
   }
 
   if (is_posix && !is_mac && !is_nacl) {
     sources += [
       "memory/shared_memory_tracker.cc",
       "memory/shared_memory_tracker.h",
     ]
   }
@@ skipping 1108 matching lines @@
 }
 
 fuzzer_test("base_json_correctness_fuzzer") {
   sources = [
     "json/correctness_fuzzer.cc",
   ]
   deps = [
     ":base",
   ]
 }