Reland of New task queueing primitive for async tasks: TaskQueue.

webrtc/base/base.gyp

Index: webrtc/base/base.gyp
diff --git a/webrtc/base/base.gyp b/webrtc/base/base.gyp
index 9cf936a57b8d6428b9ce3b2faa2380821de4404b..8eb881e8e0902f717b56f85af25b8c67815d9c6b 100644
--- a/webrtc/base/base.gyp
+++ b/webrtc/base/base.gyp
@@ -84,6 +84,12 @@
         'swap_queue.h',
         'systeminfo.cc',
         'systeminfo.h',
+        'task_queue.h',
+        'task_queue_libevent.cc',
+        'task_queue_gcd.cc',
+        'task_queue_posix.cc',
+        'task_queue_posix.h',
+        'task_queue_win.cc',
         'template_util.h',
         'thread_annotations.h',
         'thread_checker.h',
@@ -111,6 +117,24 @@
             'logging.h',
             'logging_mac.mm',
           ],
+          'conditions': [
+            ['build_libevent==1', {
+              'dependencies': [
+                '<(DEPTH)/base/third_party/libevent/libevent.gyp:libevent',
+              ],
+            }],
+          ],
+        }],
+        ['build_libevent!=1', {

[phoglund, 2016/05/16 09:59:09]

Hmm, this isn't going to work since we're always forcing build_libevent to 0 in
the downstream import (we do that since we don't want line #123, we set up our
own third-party deps there).

I've landed support for libevent downstream though, so I can just try to make a
new patch where I remove this disable logic. If you still need to keep it, you
need to introduce a new variable enable_libevent_taskqueue or something so we
can separate "depend on libevent" from "use libevent at all in WebRTC."

+          'sources!': [ 'task_queue_libevent.cc' ],
+          'conditions': [
+            ['OS=="linux" or OS=="android"', {
+              'sources!': [ 'task_queue_posix.cc' ],
+            }],
+          ],
+        }],
+        ['build_libevent==1 or OS=="linux" or OS=="android" or OS=="win"', {
+          'sources!': [ 'task_queue_gcd.cc' ],
         }],
         ['OS=="mac" and build_with_chromium==0', {
           'all_dependent_settings': {