arc-bridge: Add the ARC Bridge Service

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 9f2f91ad20e14c5ab3406debd21f85bc5eb70d36..bc5f890f91ec78c8e6bcbef1d2c8af0424fb4428 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -1545,6 +1545,9 @@
     'libjpeg_ijg_gyp_path': '<(DEPTH)/third_party/libjpeg/libjpeg.gyp',
     'libjpeg_turbo_gyp_path': '<(DEPTH)/third_party/libjpeg_turbo/libjpeg.gyp',
 
+    # ARC instance disabled by default.
+    'enable_arc%': 0,
+
     'conditions': [
       ['buildtype=="Official"', {
         # Continue to embed build meta data in Official builds, basically the
@@ -3076,6 +3079,9 @@
         # TODO: Enable on Windows too, http://crbug.com/404525
         'variables': { 'clang_warning_flags': ['-Wexit-time-destructors']},
       }],
+      ['<(enable_arc)==1', {
+        'defines': ['ENABLE_ARC=1'],
+      }],
       ['chromium_code==0', {
         'variables': {
           'clang_warning_flags': [