Add PlayerTracker and BrowserCdm interfaces.

media/base/android/media_player_android.cc

Index: media/base/android/media_player_android.cc
diff --git a/media/base/android/media_player_android.cc b/media/base/android/media_player_android.cc
index 158e520c54f5f11941e81df9bb261ab7c41418f6..b515d08e57d22afbe1dad6fefacf7ce415fb1d54 100644
--- a/media/base/android/media_player_android.cc
+++ b/media/base/android/media_player_android.cc
@@ -6,7 +6,6 @@
 
 #include "base/logging.h"
 #include "media/base/android/media_player_manager.h"
-#include "media/base/media_keys.h"
 
 namespace media {
 
@@ -31,13 +30,9 @@ GURL MediaPlayerAndroid::GetFirstPartyForCookies() {
   return GURL();
 }
 
-void MediaPlayerAndroid::SetCdm(MediaKeys* cdm) {
-  // Not all players support CDMs. Do nothing by default.
-  return;
-}
-
-void MediaPlayerAndroid::OnKeyAdded() {
-  // Not all players care about the decryption key. Do nothing by default.
+void MediaPlayerAndroid::SetCdm(BrowserCdm* /* cdm */) {
+  // Players that support EME should override this.
+  NOTREACHED() << "EME not supported on base MediaPlayerAndroid class.";
   return;
 }