Move some of IOThread's command line logic to network_session_configurator.

components/network_session_configurator/common/BUILD.gn

Index: components/network_session_configurator/common/BUILD.gn
diff --git a/components/network_session_configurator/common/BUILD.gn b/components/network_session_configurator/common/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..db3d2c6b040eee98812db6c24b5ced6ba20d1daa
--- /dev/null
+++ b/components/network_session_configurator/common/BUILD.gn
@@ -0,0 +1,15 @@
+# Copyright 2016 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.

[Ryan Hamilton, 2017/06/02 20:49:04]

This is probably obvious, but what's the difference between browser/ and
common/? Should we add a comment about that somewhere?

[mmenke, 2017/06/05 18:43:27]

It's pretty common for components to have directories with these names
(https://cs.chromium.org/search/?q=file:components/.*/browser/$+package:%5Echr...
- looks like over 100 components do this).  In general common/ can be included
by anything, and browser/ can only be included by things that live only in the
browser process (content/browser, chrome/browser, or things only they include or
that include them).  Since HttpNetworkSession can't be used in most processes,
seems like, for example, a file in content/common shouldn't be depending on it.

This is a common enough pattern that I'm not sure if it needs to be documented
(I'm also not sure about where this should be documented, if we chose to do so).

[Ryan Hamilton, 2017/06/07 18:15:44]

Ok, fair enough!

+
+static_library("common") {
+  sources = [
+    "network_switch_list.h",
+    "network_switches.cc",
+    "network_switches.h",
+  ]
+
+  public_deps = [
+    "//base",
+  ]
+}