Android: enable WebRTC H264 HW Encode for MediaTek

Matching the recents changes in libwebrtc[0] enable MediaTek just for H264

[0] https://chromium.googlesource.com/external/webrtc/+/5b6891afddcef18ea699efcd457dfab80c22ac70

BUG=848511
R=braveyao@chromium.org

Change-Id: I0431b48730eb14149530a1265d173cca7e8944f3
Reviewed-on: https://chromium-review.googlesource.com/1086408Reviewed-by: Weiyong Yao <braveyao@chromium.org>
Reviewed-by: Chrome Cunningham <chcunningham@chromium.org>
Commit-Queue: Weiyong Yao <braveyao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565033}

AUTHORS

@@ -744,6 +744,7 @@ Sayan Nayak <sayan.nayak@samsung.com>
 Scott Blomquist <sblom@microsoft.com>
 Scott D Phillips <scott.d.phillips@intel.com>
 Sean Bryant <sean@cyberwang.net>
+Sean DuBois <seaduboi@amazon.com>
 Sebastian Amend <sebastian.amend@googlemail.com>
 Seo Sanghyeon <sanxiyn@gmail.com>
 Seokju Kwon <seokju.kwon@gmail.com>

media/base/android/java/src/org/chromium/media/MediaCodecUtil.java

@@ -502,6 +502,8 @@ class MediaCodecUtil {
         ExynosVp8(MimeTypes.VIDEO_VP8, "OMX.Exynos.", Build.VERSION_CODES.M,
                 BitrateAdjuster.NO_ADJUSTMENT),
         ExynosH264(MimeTypes.VIDEO_H264, "OMX.Exynos.", Build.VERSION_CODES.LOLLIPOP,
+                BitrateAdjuster.FRAMERATE_ADJUSTMENT),
+        MediatekH264(MimeTypes.VIDEO_H264, "OMX.MTK.", Build.VERSION_CODES.O_MR1,
                 BitrateAdjuster.FRAMERATE_ADJUSTMENT);
 
         private final String mMime;