Import Cronet version 110.0.5481.154

Project import generated by Copybara.

FolderOrigin-RevId: /tmp/copybara-origin/src
Test: none
Change-Id: I534a69efa61b40fdc95613bce5bc5dd9a432f646

1 files changed, 78 insertions, 0 deletions

diff --git a/base/scoped_observation_traits.h b/base/scoped_observation_traits.h
new file mode 100644
index 000000000..7201f2658
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+++ b/base/scoped_observation_traits.h
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+// Copyright 2022 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_SCOPED_OBSERVATION_TRAITS_H_
+#define BASE_SCOPED_OBSERVATION_TRAITS_H_
+
+#include "base/scoped_observation_traits_internal.h"
+
+namespace base {
+
+// `ScopedObservationTraits` is used to control the behavior of
+// `ScopedObservation` on sources without AddObserver()/RemoveObserver()
+// methods.
+//
+// The implementation of `ScopedObservation<Source, Observer>` will look up the
+// most specialized version of `ScopedObservationTraits<Source, Observer>` and
+// use the corresponding `Traits::AddObserver` and `Traits::RemoveObserver`.
+//
+// The default specialization takes care of any Source that exposes
+// `AddObserver(Observer*)` and `RemoveObserver(Observer*)` methods -- if that's
+// the case, then `ScopedObservation<Source, Observer>` will work out of the
+// box.
+//
+// However, if your `CustomSource` features custom method names -- say,
+// `AddFoo(FooObserver*)` and `RemoveFoo(FooObserver*)`, then you'll have to
+// define a new traits specialization like this:
+//
+// `custom_source.h`:
+//    #include "base/scoped_observation_traits.h"
+//
+//    class FooObserver;
+//    class CustomSource {
+//     public:
+//      void AddFoo(FooObserver*);
+//      void RemoveFoo(FooObserver*);
+//    };
+//
+//    namespace base {
+//
+//    template<>
+//    struct ScopedObservationTraits<CustomSource, FooObserver> {
+//      static void AddObserver(CustomSource* source,
+//                              FooObserver* observer) {
+//        source->AddFoo(observer);
+//      }
+//      static void RemoveObserver(CustomSource* source,
+//                                 FooObserver* observer) {
+//        source->RemoveFoo(observer);
+//      }
+//    };
+//
+//    }  // namespace base
+//
+// `some_important_file.cc`:
+//    // Now this works out of the box.
+//    base::ScopedObservation<CustomSource, FooObserver> obs...
+//
+
+template <class Source, class Observer>
+struct ScopedObservationTraits {
+  static_assert(internal::HasAddAndRemoveObserverMethods<Source, Observer>,
+                "The given Source is missing "
+                "AddObserver(Observer*) and/or RemoveObserver(Observer*) "
+                "methods. Please provide a custom specialization of "
+                "ScopedObservationTraits<> for this Source/Observer pair.");
+
+  static void AddObserver(Source* source, Observer* observer) {
+    source->AddObserver(observer);
+  }
+  static void RemoveObserver(Source* source, Observer* observer) {
+    source->RemoveObserver(observer);
+  }
+};
+
+}  // namespace base
+
+#endif  // BASE_SCOPED_OBSERVATION_TRAITS_H_