[Cronet] Use Context's ClassLoader to load Cronet

components/cronet/android/api/src/org/chromium/net/CronetEngine.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;
 
 import android.content.Context;
 import android.net.http.HttpResponseCache;
 import android.support.annotation.IntDef;
 import android.support.annotation.Nullable;
@@ skipping 992 matching lines @@
             cronetEngine = new JavaCronetEngine(builder.getUserAgent());
         }
         Log.i(TAG, "Using network stack: " + cronetEngine.getVersionString());
         return cronetEngine;
     }
 
     private static CronetEngine createCronetEngine(Builder builder) {
         CronetEngine cronetEngine = null;
         try {
             Class<? extends CronetEngine> engineClass =
-                    CronetEngine.class.getClassLoader()
+                    builder.getContext()

[kapishnikov, 2016/06/02 16:17:47]

Is it the same context that is supplied in the constructor of the Builder class?
We should expect that the user is going to construct the Builder with the app
context or the activity context.

[pauljensen, 2016/06/03 13:24:30]

Yes
As the API stands now, yes.  However I'm proposing having another method to
construct the CronetEngine.Builder, and potentially hiding the default
CronetEngine.Builder().

+                            .getClassLoader()
                             .loadClass(CRONET_URL_REQUEST_CONTEXT)
                             .asSubclass(CronetEngine.class);
             Constructor<? extends CronetEngine> constructor =
                     engineClass.getConstructor(Builder.class);
             CronetEngine possibleEngine = constructor.newInstance(builder);
             if (possibleEngine.isEnabled()) {
                 cronetEngine = possibleEngine;
             }
         } catch (ClassNotFoundException e) {
             // Leave as null.
@@ skipping 149 matching lines @@
      * @hide as it's a prototype.
      */
     public interface RequestFinishedListener { // TODO(klm): Add a convenience abstract class.
         /**
          * Invoked with request info.
          * @param requestInfo {@link UrlRequestInfo} for finished request.
          */
         void onRequestFinished(UrlRequestInfo requestInfo);
     }
 }