Added Network Quality Estimator Real-time interface to Cronet

components/cronet/android/java/src/org/chromium/net/NetworkQualityRttObserver.java

+// Copyright 2015 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;
+
+/**
+ * Interface to watch for observations of round trip times.

[pauljensen, 2015/09/18 16:07:51]

need to clarify which round trip times you're talking about.

[bengr, 2015/09/18 23:13:42]

Done.

+ */
+public interface NetworkQualityRttObserver {
+    /**
+     * Reports a new round trip time observation. This is called on the network thread, so the

[pauljensen, 2015/09/18 16:07:52]

I don't think customers have an idea what the "network thread" is; is this
comment out of data?  is it called back on the executor?

[bengr, 2015/09/18 23:13:42]

Yeah, it is. Fixed.

+     * observer should exit quickly.
+     * @param rttMs The round trip time in milliseconds.
+     * @param whenMs The time since the epoch in milliseconds.
+     * @param source The observation source from {@link NetworkQualityObservationSource}.

[pauljensen, 2015/09/18 16:07:52]

Two big problems with NetworkQualityObservationSource:
1. No enums allowed in public APIs.  This has been endlessly discussed, but the
decision is final.  go/android-api-guidelines
2. I don't think generated enums have any comments and we need lots of comments
for public APIs.

[bengr, 2015/09/18 23:13:42]

What other option do I have?

[pauljensen, 2015/09/22 16:03:03]

You could fix up the generator (build/android/gyp/java_cpp_enum.py) to simply
copy /* */ comments through verbatim.
The other option is to write some int's by hand in Java and add some assertions
that they match the generated ones.  Note that enum's are forbayed in Android
APIs so they need to be "public final static int"'s.

[bengr, 2015/09/29 23:22:50]

Done.

+     */
+    public void onRttObservation(int rttMs, long whenMs, int source);
+}