Fix mismatched-tags error

These are exposed when frameworks/av/include is moved from being a
system include directory to a normal include directory.

Test: m -j checkbuild
Change-Id: Iaa8f3808d578ebedc75e863b9818cfbbec9080b2
diff --git a/include/media/IMediaPlayerService.h b/include/media/IMediaPlayerService.h
index 8266b0b..f21bb3a 100644
--- a/include/media/IMediaPlayerService.h
+++ b/include/media/IMediaPlayerService.h
@@ -32,7 +32,7 @@
 namespace android {
 
 struct IHDCP;
-struct IMediaCodecList;
+class IMediaCodecList;
 struct IMediaHTTPService;
 class IMediaRecorder;
 class IOMX;