Add AutoJObject and AutoGlobalJObject

base/android/auto_global_jobject.h

+// Copyright (c) 2011 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.
+
+#ifndef BASE_ANDROID_AUTO_GLOBAL_JOBJECT_H_
+#define BASE_ANDROID_AUTO_GLOBAL_JOBJECT_H_
+
+#include <jni.h>
+
+#include "base/android/auto_jobject.h"
+
+namespace base {
+namespace android {
+
+// A global reference to a Java object which is cleaned up automatically when
+// this object gets deleted.
+class AutoGlobalJObject {
+ public:
+  // Takes ownership of |obj|.
+  static AutoGlobalJObject FromLocalRef(JNIEnv* env, jobject obj);

[brettw, 2011/08/01 16:03:54]

There's not a defined place for this in the header, but the typedefs,
constructors & destructors should be first, so put this later.

[steveblock, 2011/08/02 15:05:46]

Done.

+
+  AutoGlobalJObject();
+  AutoGlobalJObject(const AutoGlobalJObject& other);

[brettw, 2011/08/01 16:03:54]

Do you need an implicit copy constructor? These are generally discouraged.

[steveblock, 2011/08/02 15:05:46]

We don't need one for AutoGlobalJObject (other than for
AutoGlobalJObject::FromLocalRef(), which can be removed), but we do need one for
AutoJObject, as we want to be able to return objects of this type by value, such
as from JavaObjectWeakGlobalRef::get()

[brettw, 2011/08/02 15:55:39]

If you're going to be returning these by value, it seems weird you wouldn't also
support operator=. Otherwise users of this will likely get confused.

+  explicit AutoGlobalJObject(const AutoJObject& obj);
+  ~AutoGlobalJObject();
+
+  void Reset();
+  void Reset(const AutoGlobalJObject& other);
+  jobject obj() const;

[brettw, 2011/08/01 16:03:54]

This should be inline. If it can't be, it should be named with CamelCase.

[steveblock, 2011/08/02 15:05:46]

Done.

+
+ private:
+  // Not permitted.
+  AutoGlobalJObject& operator=(const AutoGlobalJObject& other);
+
+  JNIEnv* env_;
+  jobject obj_;
+};
+
+}  // namespace android
+}  // namespace base
+
+#endif  // BASE_ANDROID_AUTO_GLOBAL_JOBJECT_H_