Implement IPC::ChannelFactory, a class that accept()s on a UNIX socket.

ipc/ipc.gyp

Index: ipc/ipc.gyp
diff --git a/ipc/ipc.gyp b/ipc/ipc.gyp
index 5e2f3a75203066c0701027d1fb1d99d6fde055d3..a2476511a84f2d8f62766fefdaa53b3e80d4eb06 100644
--- a/ipc/ipc.gyp
+++ b/ipc/ipc.gyp
@@ -58,6 +58,7 @@
         'ipc_test_base.cc',
         'ipc_test_base.h',
         'sync_socket_unittest.cc',
+        'unix_domain_socket_util_unittest.cc',
       ],
       'conditions': [
         ['toolkit_uses_gtk == 1', {
@@ -65,6 +66,11 @@
             '../build/linux/system.gyp:gtk',
           ],
         }],
+        ['OS == "win" or OS == "ios"', {
+          'sources!': [
+            'unix_domain_socket_util_unittest.cc',
+          ],
+        }],
         ['OS == "android" and gtest_target_type == "shared_library"', {
           'dependencies': [
             '../testing/android/native_test.gyp:native_test_native_code',