WebRTC: Build Chromium with codecs

scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Win8_Tester.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]\\scripts\\slave\\kill_processes.py"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "taskkill"
   },
@@ skipping 107 matching lines @@
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]\\gclient.py",
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
-      "GYP_DEFINES": "chromium_win_pch=0 component=static_library fastbuild=1 gomadir='[BUILD]\\goma' target_arch=ia32 use_goma=1"
+      "GYP_DEFINES": "chromium_win_pch=0 component=static_library fastbuild=1 ffmpeg_branding=Chrome gomadir='[BUILD]\\goma' proprietary_codecs=1 target_arch=ia32 use_goma=1"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]\\src\\testing\\scripts\\get_compile_targets.py",
       "--output",
       "/path/to/tmp/json",
@@ skipping 241 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "process_dumps"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]