Make GetApplicationContext return a JavaRef.

ui/android/window_android.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/android/window_android.h"
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
 #include "jni/WindowAndroid_jni.h"
 #include "ui/android/window_android_compositor.h"
 #include "ui/android/window_android_observer.h"
 
 namespace ui {
 
 using base::android::AttachCurrentThread;
 using base::android::JavaParamRef;
+using base::android::JavaRef;
 using base::android::ScopedJavaLocalRef;
 
 WindowAndroid::WindowAndroid(JNIEnv* env, jobject obj) : compositor_(NULL) {
   java_window_.Reset(env, obj);
 }
 
 void WindowAndroid::Destroy(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   delete this;
 }
 
 ScopedJavaLocalRef<jobject> WindowAndroid::GetJavaObject() {
   return base::android::ScopedJavaLocalRef<jobject>(java_window_);
 }
 
 bool WindowAndroid::RegisterWindowAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 WindowAndroid::~WindowAndroid() {
   DCHECK(parent_ == nullptr) << "WindowAndroid must be a root view.";
   DCHECK(!compositor_);
 }
 
 WindowAndroid* WindowAndroid::createForTesting() {
   JNIEnv* env = AttachCurrentThread();
-  jobject context = base::android::GetApplicationContext();
+  const JavaRef<jobject>& context = base::android::GetApplicationContext();
   return new WindowAndroid(
       env, Java_WindowAndroid_createForTesting(env, context).obj());
 }
 
 void WindowAndroid::OnCompositingDidCommit() {
   FOR_EACH_OBSERVER(WindowAndroidObserver,
                     observer_list_,
                     OnCompositingDidCommit());
 }
 
@@ skipping 95 matching lines @@
 // ----------------------------------------------------------------------------
 // Native JNI methods
 // ----------------------------------------------------------------------------
 
 jlong Init(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   WindowAndroid* window = new WindowAndroid(env, obj);
   return reinterpret_cast<intptr_t>(window);
 }
 
 }  // namespace ui