[Cronet] Expose HttpURLConnection API from CronetEngine, not classes

components/cronet/README.md

 # Quick Start Guide to Using Cronet
 Cronet is the networking stack of Chromium put into a library for use on
 mobile. This is the same networking stack that is used in the Chrome browser
 by over a billion people. It offers an easy-to-use, high performance,
 standards-compliant, and secure way to perform HTTP requests. Cronet has support
 for both Android and iOS. On Android, Cronet offers its own Java asynchronous
 API as well as support for the [java.net.HttpURLConnection] API.
 This document gives a brief introduction to using these two Java APIs.
 
 ### Basics
@@ skipping 126 matching lines @@
 To get more information about how Cronet is processing network
 requests, you can start and stop **NetLog** logging by calling
 `CronetEngine.startNetLogToFile` and `CronetEngine.stopNetLog`.
 Bear in mind that logs may contain sensitive data. You may analyze the
 generated log by navigating to [chrome://net-internals#import] using a
 Chrome browser.
 
 # Using the java.net.HttpURLConnection API
 Cronet offers an implementation of the [java.net.HttpURLConnection] API to make
 it easier for apps which rely on this API to use Cronet.
-To use Cronet's implementation instead of the system's default implementation,
-simply do the following:
+To open individual connections using Cronet's implementation, do the following:
 
-    CronetURLStreamHandlerFactory streamHandlerFactory =
-            new CronetURLStreamHandlerFactory(engine);
-    URL.setURLStreamHandlerFactory(streamHandlerFactory);
+    HttpURLConnection connection =
+            (HttpURLConnection)engine.openConnection(url);
+
+To use Cronet's implementation instead of the system's default implementation
+for all connections established using `URL.openConnection()` do the following:
+
+    URL.setURLStreamHandlerFactory(engine.createURLStreamHandlerFactory());
 
 Cronet's
 HttpURLConnection implementation has some limitations as compared to the system
 implementation, including not utilizing the default system HTTP cache (Please
-see {@link org.chromium.net.urlconnection.CronetURLStreamHandlerFactory} for
+see {@link org.chromium.net.CronetEngine#createURLStreamHandlerFactory} for
 more information).
 You can configure Cronet and control caching through the
 `CronetEngine.Builder` instance, `engineBuilder`
-(See [Configuring Cronet](#configuring-cronet) section), before you pass it
-into the `CronetURLStreamHandlerFactory` constructor.
+(See [Configuring Cronet](#configuring-cronet) section), before you build the
+`CronetEngine` and then call `CronetEngine.createURLStreamHandlerFactory()`.
 
 [ByteBuffer]: https://developer.android.com/reference/java/nio/ByteBuffer.html
 [chrome://net-internals#import]: chrome://net-internals#import
 [java.net.HttpURLConnection]: https://developer.android.com/reference/java/net/HttpURLConnection.html