Cronet API Refactoring

components/cronet/android/api/src/org/chromium/net/ExperimentalBidirectionalStream.java

+// Copyright 2016 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.
+
+package org.chromium.net;
+
+/**
+ * {@link BidirectionalStream} that exposes experimental features.
+ * Created using {@link ExperimentalBidirectionalStream.Builder}.
+ *
+ * {@hide} as it's a prototype
+ */
+public abstract class ExperimentalBidirectionalStream extends BidirectionalStream {
+    /**
+     * Builder for {@link ExperimentalBidirectionalStream}s. Allows configuring stream before
+     * constructing it via {@link Builder#build}.
+     */
+    public abstract static class Builder extends BidirectionalStream.Builder {
+        /**
+         * Associates the annotation object with this request. May add more than one.
+         * Passed through to a {@link RequestFinishedInfo.Listener},
+         * see {@link RequestFinishedInfo#getAnnotations}.
+         *
+         * @param annotation an object to pass on to the {@link RequestFinishedInfo.Listener} with a
+         * {@link RequestFinishedInfo}.
+         * @return the builder to facilitate chaining.
+         */
+        public abstract Builder addRequestAnnotation(Object annotation);
+    }

[pauljensen, 2016/09/26 14:51:21]

So I've an idea:
We were wondering how to deal with the fact that Experimental Builders will
return the base Builder class from all setters.  What about using covariant
return types to address this?  We could @Override every Builder method in the
Experimental.Builder classes and make them return the Experimental.Builder
classes exploiting covariant return types.  This way clients only need to cast
the Builder to the Experimental.Builder class once.

[kapishnikov, 2016/09/27 18:38:25]

Done. Same for ExperimentalCronetEngine & ExperimentalUrlRequest.

+}