Add API for custom library loading

components/cronet/android/java/src/org/chromium/net/CronetLibraryLoader.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.os.Handler;
 import android.os.Looper;
 
@@ skipping 14 matching lines @@
     /**
      * Ensure that native library is loaded and initialized. Can be called from
      * any thread, the load and initialization is performed on main thread.
      */
     public static void ensureInitialized(
             final Context context, final CronetEngine.Builder builder) {
         synchronized (sLoadLock) {
             if (sInitTaskPosted) {
                 return;
             }
-            System.loadLibrary(builder.libraryName());
+            builder.loadLibrary();
             if (!Version.CRONET_VERSION.equals(nativeGetCronetVersion())) {
                 throw new RuntimeException(String.format(
                       "Expected Cronet version number %s, "
                               + "actual version number %s.",
                       Version.CRONET_VERSION,
                       nativeGetCronetVersion()));
             }
             ContextUtils.initApplicationContext(context.getApplicationContext());
             // Init native Chromium CronetEngine on Main UI thread.
             Runnable task = new Runnable() {
@@ skipping 21 matching lines @@
         // observers. Existing observers in the net stack do not
         // perform expensive work.
         NetworkChangeNotifier.registerToReceiveNotificationsAlways();
         // registerToReceiveNotificationsAlways() is called before the native
         // NetworkChangeNotifierAndroid is created, so as to avoid receiving
         // the undesired initial network change observer notification, which
         // will cause active requests to fail with ERR_NETWORK_CHANGED.
         nativeCronetInitOnMainThread();
     }
 
-    // Native methods are implemented in cronet_loader.cc.
+    // Native methods are implemented in cronet_library_loader.cc.
     private static native void nativeCronetInitOnMainThread();
     private static native String nativeGetCronetVersion();
 }