Introduce pdfium::FakeUniquePtr for keys to sets of unique ptrs.

third_party/base/stl_util.h

Index: third_party/base/stl_util.h
diff --git a/third_party/base/stl_util.h b/third_party/base/stl_util.h
index 2d1846724c3094161ce910986fd13be10c7b9f62..013a4c8bc17479f59d9501ce3a94ea630273ba66 100644
--- a/third_party/base/stl_util.h
+++ b/third_party/base/stl_util.h
@@ -27,6 +27,15 @@ bool ContainsValue(const Collection& collection, const Value& value) {
          collection.end();
 }
 
+// Means of generating a key for std::set<std::unique_ptr> that avoids

[brucedawson, 2016/08/19 20:59:46]

std::set is no longer correct for its first use. Perhaps rephrase? Not crucial,
but maybe something like:

Means of generating a key for searching STL containers that avoids the side
effect of deleting the pointer.

[Tom Sepez, 2016/08/19 21:16:42]

Done.

+// the side effect of destroying the key.
+template <class T>
+class LeakPtr : public std::unique_ptr<T> {

[brucedawson, 2016/08/19 20:59:46]

The name is not intuitively meaningful to me. I'm not sure what would be better.
NownOwningUniquePtr?

[Tom Sepez, 2016/08/19 21:16:42]

I've thought of (modulo hyphens and camelCase):

duplicate_ptr
duplicated_ptr
duplicate_unique_ptr
leaky_unique_ptr
non_unique_ptr
fake_unique_ptr
non_deleting_unique_ptr

There's a certain humor to NonUniquePtr(), maybe go with that?

+ public:
+  using std::unique_ptr<T>::unique_ptr;
+  ~LeakPtr() { std::unique_ptr<T>::release(); }
+};
+
 // Convenience routine for "int-fected" code, so that the stl collection
 // size_t size() method return values will be checked.
 template <typename ResultType, typename Collection>