Cronet Java wrappers to fallback to HttpUrlConnection if Cronet is not available.

net/cronet/android/java/src/org/chromium/net/HttpUrlRequestFactory.java

Index: net/cronet/android/java/src/org/chromium/net/HttpUrlRequestFactory.java
diff --git a/net/cronet/android/java/src/org/chromium/net/HttpUrlRequestFactory.java b/net/cronet/android/java/src/org/chromium/net/HttpUrlRequestFactory.java
new file mode 100644
index 0000000000000000000000000000000000000000..145879ac2c16e447f5ce27c746392dae66df0d91
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+++ b/net/cronet/android/java/src/org/chromium/net/HttpUrlRequestFactory.java
@@ -0,0 +1,95 @@
+// Copyright 2014 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.util.Log;
+
+import java.lang.reflect.Constructor;
+import java.nio.channels.WritableByteChannel;
+import java.util.Map;
+
+/**
+ * A factory for {@link HttpUrlRequest}'s, which uses the best HTTP stack available on
+ * the current platform.
+ */
+public abstract class HttpUrlRequestFactory {
+
+  private static final String TAG = "HttpUrlRequestFactory";
+
+  private static final String CHROMIUM_URL_REQUEST_FACTORY =
+      "org.chromium.net.ChromiumUrlRequestFactory";
+
+  private static HttpUrlRequestFactory sFactory;
+
+  private static synchronized HttpUrlRequestFactory getFactory(Context context) {
+    if (sFactory == null) {
+      try {
+        Class<? extends HttpUrlRequestFactory> factoryClass =
+            HttpUrlRequestFactory.class.getClassLoader()
+                .loadClass(CHROMIUM_URL_REQUEST_FACTORY)
+                .asSubclass(HttpUrlRequestFactory.class);
+        Constructor<? extends HttpUrlRequestFactory> constructor =
+            factoryClass.getConstructor(Context.class);
+        HttpUrlRequestFactory chromiumFactory = constructor.newInstance(context);
+        if (chromiumFactory.isEnabled()) {
+          sFactory = chromiumFactory;
+        }
+      } catch (ClassNotFoundException e) {
+        // Leave as null
+      } catch (Exception e) {
+        throw new IllegalStateException(
+            "Cannot instantiate: " + CHROMIUM_URL_REQUEST_FACTORY, e);
+      }
+      if (sFactory == null) {
+        // Default to HttpUrlConnection-based networking.
+        sFactory = new HttpUrlConnectionUrlRequestFactory(context);
+      }
+      Log.i(TAG, "Using network stack: " + sFactory.getName());
+    }
+    return sFactory;
+  }
+
+  /**
+   * Creates a new request intended for full-response buffering.
+   */
+  public static HttpUrlRequest newRequest(
+      Context context, String url, int requestPriority, Map<String, String> headers,
+      HttpUrlRequestListener listener) {
+    return getFactory(context).createRequest(url, requestPriority, headers, listener);
+  }
+
+  /**
+   * Creates a new request intended for streaming the response.
+   */
+  public static HttpUrlRequest newRequest(
+      Context context, String url, int requestPriority, Map<String, String> headers,
+      WritableByteChannel channel, HttpUrlRequestListener listener) {
+    return getFactory(context).createRequest(url, requestPriority, headers, channel, listener);
+  }
+
+  /**
+   * Returns true if the factory is enabled.
+   */
+  protected abstract boolean isEnabled();
+
+  /**
+   * Returns a human-readable name of the factory.
+   */
+  protected abstract String getName();
+
+  /**
+   * Creates a new request intended for full-response buffering.
+   */
+  protected abstract HttpUrlRequest createRequest(String url, int requestPriority,
+      Map<String, String> headers, HttpUrlRequestListener listener);
+
+  /**
+   * Creates a new request intended for streaming.
+   */
+  protected abstract HttpUrlRequest createRequest(String url, int requestPriority,
+      Map<String, String> headers, WritableByteChannel channel,
+      HttpUrlRequestListener listener);
+}