Remove Exynos from MediaCodec blacklist. Limit MediaTek blacklist.

media/base/android/media_codec_util.h

Index: media/base/android/media_codec_util.h
diff --git a/media/base/android/media_codec_util.h b/media/base/android/media_codec_util.h
index 04b83a9937299f67e8b3e80066d508ff436062d5..a6f1336873fe0210d749e5dc694e53198d300591 100644
--- a/media/base/android/media_codec_util.h
+++ b/media/base/android/media_codec_util.h
@@ -66,8 +66,9 @@ class MEDIA_EXPORT MediaCodecUtil {
 
   static bool RegisterMediaCodecUtil(JNIEnv* env);
 
-  // Indicates if the vp8 decoder is available on this device.
+  // Indicates if the vp8 decoder or encoder is available on this device.
   static bool IsVp8DecoderAvailable();
+  static bool IsVp8EncoderAvailable();
 };
 
 }  // namespace media