Revert "Define cricket::MediaType in terms of webrtc::MediaType"

This reverts commit 3ce6391b38397d107478041299fa998500e4fc42.

Reason for revert: Breaks downstream test

Original change's description:
> Define cricket::MediaType in terms of webrtc::MediaType
>
> This is one step in getting rid of cricket::MediaType.
>
> Bug: webrtc:12754
> Fixes: webrtc:12764
> Change-Id: Idee832572bdc4c0e3bfdec6fb31ec0ba9db3e995
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/218346
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#33994}

TBR=mbonadei@webrtc.org,hta@webrtc.org,webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: I64772018dea55e4f0946464364a60a39cec7e9ec
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:12754
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/218603
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34000}

sdk/android/api/org/webrtc/MediaStreamTrack.java

@@ -30,8 +30,8 @@ public class MediaStreamTrack {
 
   // Must be kept in sync with cricket::MediaType.
   public enum MediaType {
-    MEDIA_TYPE_AUDIO(1),
-    MEDIA_TYPE_VIDEO(2);
+    MEDIA_TYPE_AUDIO(0),
+    MEDIA_TYPE_VIDEO(1);
 
     private final int nativeIndex;