Switch from build-time to run-time flags for Project Spitzer.

media/media.gyp

Index: media/media.gyp
diff --git a/media/media.gyp b/media/media.gyp
index c8970d1f6f35068cbb78d91af55f244110f185f1..b6304d23df54aa2443509adb0cc023c9a8e12af7 100644
--- a/media/media.gyp
+++ b/media/media.gyp
@@ -748,20 +748,13 @@
               'defines': [
                 # On Android, FFmpeg is built without video decoders. We only
                 # support hardware video decoding.
-                'ENABLE_MEDIA_PIPELINE_ON_ANDROID',
                 'DISABLE_FFMPEG_VIDEO_DECODERS',
               ],
               'direct_dependent_settings': {
                 'defines': [
-                  'ENABLE_MEDIA_PIPELINE_ON_ANDROID',
                   'DISABLE_FFMPEG_VIDEO_DECODERS',
                 ],
               },
-            }, {  # media_use_ffmpeg == 0
-              'sources!': [
-                'filters/opus_audio_decoder.cc',
-                'filters/opus_audio_decoder.h',
-              ],
             }],
           ],
         }],