Introduce SystemNetworkContextManager.

chrome/browser/DEPS

 include_rules = [
   "+apps",
   "+cc/paint",
   "+chrome/app",
   "+chrome/chrome_watcher",
   "+chrome/grit",
   "+chrome/install_static",
   "+chrome/installer/util",
   "+chrome_elf/blacklist",
   "+chrome_elf/chrome_elf_constants.h",
@@ skipping 70 matching lines @@
   "+chrome/browser/ui/views/chrome_browser_main_extra_parts_views.h",
   "+chrome/browser/ui/views/chrome_browser_main_extra_parts_views_linux.h",
   "+chrome/browser/ui/views/extensions/request_file_system_dialog_view.h",
   "+chrome/browser/ui/views/try_chrome_dialog_view.h",
   "+chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.h",
 
   # Explicitly disallow using SyncMessageFilter to prevent browser from
   # sending synchronous IPC messages on non-UI threads.
   "-ipc/ipc_sync_message_filter.h",
 
+  # Allow in-proces network service. Remove once OOP NetworkService ships.

[jam, 2017/07/08 01:30:08]

nit: I think removing this wouldn't depend on the "OOP" part right? i.e. once
network service is shipped, we should use the same mojo codepaths even when it's
in-process. Then we can remove this deps entry right?

[mmenke, 2017/07/10 15:52:21]

Done.

+  "+content/public/network",
+
   # Other libraries.
   "+libxml",
   "+third_party/google_toolbox_for_mac/src",
   "+third_party/icu/source/common/unicode",
   "+third_party/icu/source/i18n/unicode",
   "+third_party/leveldatabase",
   "+third_party/libxml",
   "+third_party/mozilla",     # Mozilla interface headers.
   "+third_party/ocmock/gtest_support.h",
   "+third_party/protobuf/src/google/protobuf",
@@ skipping 37 matching lines @@
   "+third_party/WebKit/public/web/WebTextDirection.h",
   "+third_party/WebKit/public/web/window_features.mojom.h",
 ]
 specific_include_rules = {
   # TODO(mash): Remove. http://crbug.com/678705
   "fullscreen_chromeos\.cc": [
     "+ash/root_window_controller.h",
     "+ash/shell.h",
   ]
 }