[Cronet] Change interface APIs to abstract classes

components/cronet/README.md

Index: components/cronet/README.md
diff --git a/components/cronet/README.md b/components/cronet/README.md
index 22aca16a4a4363afc2a88044b36175365beaa327..bc35eec77947f8483363fc9c16c8b9586df8961f 100644
--- a/components/cronet/README.md
+++ b/components/cronet/README.md
@@ -8,10 +8,10 @@ API as well as support for the [java.net.HttpURLConnection] API.
 This document gives a brief introduction to using these two Java APIs.
 
 ### Basics
-First you will need to implement the `UrlRequestListener` interface to handle
+First you will need to implement a subclass of `UrlRequestListener` to handle
 events during the lifetime of a request. For example:
 
-    class MyListener implements UrlRequestListener {
+    class MyListener extends UrlRequestListener {
         @Override
         public void onReceivedRedirect(UrlRequest request,
                 ResponseInfo responseInfo, String newLocationUrl) {
@@ -77,9 +77,9 @@ Make a request like this:
             "https://www.example.com", listener, executor);
     request.start();
 
-In the above example, `MyListener` implements the `UrlRequestListener`
-interface. The request is started asynchronously. When the response is ready
-(fully or partially), and in the event of failures or redirects,
+In the above example, `MyListener` implements a subclass of
+`UrlRequestListener`. The request is started asynchronously. When the response
+is ready (fully or partially), and in the event of failures or redirects,
 `listener`'s methods will be invoked on `executor`'s thread to inform the
 client of the request state and/or response information.
 
@@ -103,8 +103,8 @@ which signals the completion of the request.
     request.setUploadDataProvider(myUploadDataProvider, executor);
     request.start();
 
-In the above example, `MyUploadDataProvider` implements the
-`UploadDataProvider` interface. When Cronet is ready to send the request body,
+In the above example, `MyUploadDataProvider` implements a subclass of
+`UploadDataProvider`. When Cronet is ready to send the request body,
 `myUploadDataProvider.read(UploadDataSink uploadDataSink,
 ByteBuffer byteBuffer)` will be invoked. The client will need to write the
 request body into `byteBuffer`. Once the client is done writing into