Remove unused field from MediaMuxer

Change-Id: If1ebb2302654b64924084a52425366f1b69c7c30

media/java/android/media/MediaMuxer.java

@@ -65,8 +65,6 @@ import java.util.Map;
 
 final public class MediaMuxer {
 
-    private long mNativeContext;
-
     static {
         System.loadLibrary("media_jni");
     }

media/jni/android_media_MediaMuxer.cpp

@@ -31,7 +31,6 @@
 namespace android {
 
 struct fields_t {
-    jfieldID context;
     jmethodID arrayID;
 };
 
@@ -252,12 +251,6 @@ int register_android_media_MediaMuxer(JNIEnv *env) {
     int err = AndroidRuntime::registerNativeMethods(env,
                 "android/media/MediaMuxer", gMethods, NELEM(gMethods));
 
-    jclass clazz = env->FindClass("android/media/MediaMuxer");
-    CHECK(clazz != NULL);
-
-    gFields.context = env->GetFieldID(clazz, "mNativeContext", "J");
-    CHECK(gFields.context != NULL);
-
     jclass byteBufClass = env->FindClass("java/nio/ByteBuffer");
     CHECK(byteBufClass != NULL);