GN: Work on Linux build defines

build/gyp_chromium

Index: build/gyp_chromium
diff --git a/build/gyp_chromium b/build/gyp_chromium
index ae1d4c2f66242d7c883b990078479bfd92f86836..90799f7f6b19de74817087fa2d1f0f1e903c56dd 100755
--- a/build/gyp_chromium
+++ b/build/gyp_chromium
@@ -207,6 +207,10 @@ def GetArgsStringForGN(supplemental_files):
       ('clang', '1', 'is_clang=true'),
       ('clang_use_chrome_plugins', '0', 'clang_use_chrome_plugins=false'),
       ('disable_glibcxx_debug', '1', 'disable_iterator_debugging=true'),
+      ('enable_mdns', '0', 'enable_mdns=false'),
+      ('enable_mdns', '1', 'enable_mdns=true'),
+      ('enable_plugins', '0', 'enable_plugins=false'),
+      ('enable_plugins', '1', 'enable_plugins=true'),
       ('target_arch', 'ia32', 'cpu_arch="x86"'),
       ('target_arch', 'x64', 'cpu_arch="x64" force_win64=true'),
       ('target_arch', 'arm', 'cpu_arch="arm"'),
@@ -219,6 +223,8 @@ def GetArgsStringForGN(supplemental_files):
       ('chromeos', '1', 'os="chromeos"'),
       ('use_aura', '1', 'use_aura=true'),
       ('use_goma', '1', 'use_goma=true'),
+      ('use_openssl', '0', 'use_openssl=false'),
+      ('use_openssl', '1', 'use_openssl=true'),
       ('asan', '1', 'is_asan=true'),
       ('lsan', '1', 'is_lsan=true'),
       ('msan', '1', 'is_msan=true'),