Make GetApplicationContext return a JavaRef.

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 7e202ad31fb6d202b174a43c28f0d606c7a061d4..16ea8673bae7e2baedfeacc4b3899ce873e978bb 100644
--- a/media/base/android/media_player_android.cc
+++ b/media/base/android/media_player_android.cc
@@ -7,12 +7,15 @@
 #include <algorithm>
 
 #include "base/android/context_utils.h"
+#include "base/android/scoped_java_ref.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "media/base/android/media_drm_bridge.h"
 #include "media/base/android/media_player_manager.h"
 
+using base::android::JavaRef;
+
 namespace {
 
 const double kDefaultVolume = 1.0;
@@ -106,11 +109,10 @@ void MediaPlayerAndroid::OnSeekComplete() {
 
 void MediaPlayerAndroid::OnMediaPrepared() {}
 
-void MediaPlayerAndroid::AttachListener(jobject j_media_player) {
-  jobject j_context = base::android::GetApplicationContext();
-  DCHECK(j_context);
-
-  listener_->CreateMediaPlayerListener(j_context, j_media_player);
+void MediaPlayerAndroid::AttachListener(
+    const JavaRef<jobject>& j_media_player) {
+  listener_->CreateMediaPlayerListener(base::android::GetApplicationContext(),
+                                       j_media_player);
 }
 
 void MediaPlayerAndroid::DetachListener() {