[iOS/OS X] Allow base::scoped_nsobject<> to be used when ARC is enabled.

base/mac/scoped_typeref.h

Index: base/mac/scoped_typeref.h
diff --git a/base/mac/scoped_typeref.h b/base/mac/scoped_typeref.h
index 11767186455e0aa859d0a7b9705372f472e868e2..b8d8a142625bb3f524786dae5078b6d95347149f 100644
--- a/base/mac/scoped_typeref.h
+++ b/base/mac/scoped_typeref.h
@@ -54,7 +54,7 @@ class ScopedTypeRef {
   typedef T element_type;
 
   explicit ScopedTypeRef(
-      T object = Traits::InvalidValue(),
+      __unsafe_unretained T object = Traits::InvalidValue(),
       base::scoped_policy::OwnershipPolicy policy = base::scoped_policy::ASSUME)
       : object_(object) {
     if (object_ && policy == base::scoped_policy::RETAIN)
@@ -97,9 +97,9 @@ class ScopedTypeRef {
     return &object_;
   }
 
-  void reset(T object = Traits::InvalidValue(),
+  void reset(__unsafe_unretained T object = Traits::InvalidValue(),
              base::scoped_policy::OwnershipPolicy policy =
-                base::scoped_policy::ASSUME) {
+                 base::scoped_policy::ASSUME) {
     if (object && policy == base::scoped_policy::RETAIN)
       object = Traits::Retain(object);
     if (object_)
@@ -107,24 +107,16 @@ class ScopedTypeRef {
     object_ = object;
   }
 
-  bool operator==(T that) const {
-    return object_ == that;
-  }
+  bool operator==(__unsafe_unretained T that) const { return object_ == that; }
 
-  bool operator!=(T that) const {
-    return object_ != that;
-  }
+  bool operator!=(__unsafe_unretained T that) const { return object_ != that; }
 
-  operator T() const {
-    return object_;
-  }
+  operator T() const __attribute((ns_returns_not_retained)) { return object_; }
 
-  T get() const {
-    return object_;
-  }
+  T get() const __attribute((ns_returns_not_retained)) { return object_; }
 
   void swap(ScopedTypeRef& that) {
-    T temp = that.object_;
+    __unsafe_unretained T temp = that.object_;
     that.object_ = object_;
     object_ = temp;
   }
@@ -132,14 +124,14 @@ class ScopedTypeRef {
   // ScopedTypeRef<>::release() is like std::unique_ptr<>::release.  It is NOT
   // a wrapper for Release().  To force a ScopedTypeRef<> object to call
   // Release(), use ScopedTypeRef<>::reset().
-  T release() WARN_UNUSED_RESULT {
-    T temp = object_;
+  T release() __attribute((ns_returns_not_retained)) WARN_UNUSED_RESULT {
+    __unsafe_unretained T temp = object_;
     object_ = Traits::InvalidValue();
     return temp;
   }
 
  private:
-  T object_;
+  __unsafe_unretained T object_;
 };
 
 }  // namespace base