Make ffmpeg specific unit_tests depend on media_use_ffmpeg

Media unit tests depending on ffmpeg are currently only removed
using OS=="android", but let's remove them based on
media_use_ffmpeg==0 instead.

BUG=410779
R=acolwell@chromium.org

Review URL: https://codereview.chromium.org/541553003

Cr-Commit-Position: refs/heads/master@{#294148}

media/BUILD.gn

@@ -506,7 +506,9 @@ test("media_unittests") {
       # TODO(GYP)
       #"//testing/android:native_test_native_code"
     ]
-  } else {
+  }
+
+  if (media_use_ffmpeg) {
     sources += [
       "ffmpeg/ffmpeg_common_unittest.cc",
       "filters/audio_decoder_unittest.cc",

media/media.gyp

@@ -1237,7 +1237,19 @@
         }, {  # media_use_ffmpeg== 0
           'sources!': [
             'base/audio_video_metadata_extractor_unittest.cc',
+            'base/container_names_unittest.cc',
             'base/media_file_checker_unittest.cc',
+            'ffmpeg/ffmpeg_common_unittest.cc',
+            'filters/audio_decoder_unittest.cc',
+            'filters/audio_file_reader_unittest.cc',
+            'filters/blocking_url_protocol_unittest.cc',
+            'filters/ffmpeg_demuxer_unittest.cc',
+            'filters/ffmpeg_glue_unittest.cc',
+            'filters/ffmpeg_h264_to_annex_b_bitstream_converter_unittest.cc',
+            'filters/ffmpeg_video_decoder_unittest.cc',
+            'filters/in_memory_url_protocol_unittest.cc',
+            'filters/pipeline_integration_test.cc',
+            'filters/pipeline_integration_test_base.cc',
           ],
         }],
         ['use_alsa==1', {
@@ -1262,18 +1274,6 @@
         ['OS=="android"', {
           'sources!': [
             'audio/audio_input_volume_unittest.cc',
-            'base/container_names_unittest.cc',
-            'ffmpeg/ffmpeg_common_unittest.cc',
-            'filters/audio_decoder_unittest.cc',
-            'filters/audio_file_reader_unittest.cc',
-            'filters/blocking_url_protocol_unittest.cc',
-            'filters/ffmpeg_demuxer_unittest.cc',
-            'filters/ffmpeg_glue_unittest.cc',
-            'filters/ffmpeg_h264_to_annex_b_bitstream_converter_unittest.cc',
-            'filters/ffmpeg_video_decoder_unittest.cc',
-            'filters/in_memory_url_protocol_unittest.cc',
-            'filters/pipeline_integration_test.cc',
-            'filters/pipeline_integration_test_base.cc',
           ],
           'dependencies': [
             '../testing/android/native_test.gyp:native_test_native_code',