Create BUILD.gn files for //media/filters.

media/base/BUILD.gn

Index: media/base/BUILD.gn
diff --git a/media/base/BUILD.gn b/media/base/BUILD.gn
index a4c5a309e029a563ff64d80ad5cd215ffd99d59c..84542032c399c955259532208ca9f88c5a503d13 100644
--- a/media/base/BUILD.gn
+++ b/media/base/BUILD.gn
@@ -304,12 +304,16 @@ target(link_target_type, "base") {
         "media_file_checker.cc",
         "media_file_checker.h",
       ]
-      deps += [ "//media:filters_common" ]
+      deps += [ "//media/filters:filters_common" ]
     }
 
     deps += [ "//third_party/ffmpeg" ]
   }
 
+  if (media_use_libvpx) {
+    deps += [ "//third_party/libvpx" ]
+  }
+
   if (is_android) {
     public_deps += [
       "//media/base/android",