Support desktop media pipeline on Android for GN build.

media/base/BUILD.gn

Index: media/base/BUILD.gn
diff --git a/media/base/BUILD.gn b/media/base/BUILD.gn
index 3565553d7523197eba2f08fe687ea53a78e0a85b..70d9dd15e2e13e63473b6fae47f9b9464aacf2ff 100644
--- a/media/base/BUILD.gn
+++ b/media/base/BUILD.gn
@@ -220,13 +220,17 @@ source_set("base") {
 
   if (media_use_ffmpeg) {
     sources += [
-      "audio_video_metadata_extractor.cc",
-      "audio_video_metadata_extractor.h",
       "container_names.cc",
       "container_names.h",
-      "media_file_checker.cc",
-      "media_file_checker.h",
     ]
+    if (!is_android) {
+      sources += [
+        "audio_video_metadata_extractor.cc",
+        "audio_video_metadata_extractor.h",
+        "media_file_checker.cc",
+        "media_file_checker.h",
+      ]
+    }
 
     deps += [ "//third_party/ffmpeg" ]
   }