[Cronet] Add ExperimentalCronetEngine.Builder.setThreadPriority() API

components/cronet/android/java/src/org/chromium/net/impl/JavaCronetEngine.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.impl;
 
 import static android.os.Process.THREAD_PRIORITY_BACKGROUND;
 import static android.os.Process.THREAD_PRIORITY_MORE_FAVORABLE;
 
 import org.chromium.net.BidirectionalStream;
@@ skipping 17 matching lines @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
 
 /**
  * {@link java.net.HttpURLConnection} backed CronetEngine.
  *
  * <p>Does not support netlogs, transferred data measurement, bidistream, cache, or priority.
  */
 public final class JavaCronetEngine extends CronetEngineBase {
     private final String mUserAgent;
+    private final ExecutorService mExecutorService;
 
-    private final ExecutorService mExecutorService =
-            Executors.newCachedThreadPool(new ThreadFactory() {
-                @Override
-                public Thread newThread(final Runnable r) {
-                    return Executors.defaultThreadFactory().newThread(new Runnable() {
-                        @Override
-                        public void run() {
-                            Thread.currentThread().setName("JavaCronetEngine");
-                            // On android, all background threads (and all threads that are part
-                            // of background processes) are put in a cgroup that is allowed to
-                            // consume up to 5% of CPU - these worker threads spend the vast
-                            // majority of their time waiting on I/O, so making them contend with
-                            // background applications for a slice of CPU doesn't make much sense.
-                            // We want to hurry up and get idle.
-                            android.os.Process.setThreadPriority(
-                                    THREAD_PRIORITY_BACKGROUND + THREAD_PRIORITY_MORE_FAVORABLE);
-                            r.run();
-                        }
-                    });
-                }
-            });
-
-    public JavaCronetEngine(String userAgent) {
-        this.mUserAgent = userAgent;
+    public JavaCronetEngine(CronetEngineBuilderImpl builder) {
+        // On android, all background threads (and all threads that are part
+        // of background processes) are put in a cgroup that is allowed to
+        // consume up to 5% of CPU - these worker threads spend the vast
+        // majority of their time waiting on I/O, so making them contend with
+        // background applications for a slice of CPU doesn't make much sense.
+        // We want to hurry up and get idle.
+        final int threadPriority =
+                builder.threadPriority(THREAD_PRIORITY_BACKGROUND + THREAD_PRIORITY_MORE_FAVORABLE);
+        this.mUserAgent = builder.getUserAgent();
+        this.mExecutorService = Executors.newCachedThreadPool(new ThreadFactory() {
+            @Override
+            public Thread newThread(final Runnable r) {
+                return Executors.defaultThreadFactory().newThread(new Runnable() {
+                    @Override
+                    public void run() {
+                        Thread.currentThread().setName("JavaCronetEngine");
+                        android.os.Process.setThreadPriority(threadPriority);
+                        r.run();
+                    }
+                });
+            }
+        });
     }
 
     @Override
     public UrlRequestBase createRequest(String url, UrlRequest.Callback callback, Executor executor,
             int priority, Collection<Object> connectionAnnotations, boolean disableCache,
             boolean disableConnectionMigration, boolean allowDirectExecutor) {
         return new JavaUrlRequest(
                 callback, mExecutorService, executor, url, mUserAgent, allowDirectExecutor);
     }
 
@@ skipping 100 matching lines @@
         // Returning null causes this factory to pass though, which ends up using the platform's
         // implementation.
         return new URLStreamHandlerFactory() {
             @Override
             public URLStreamHandler createURLStreamHandler(String protocol) {
                 return null;
             }
         };
     }
 }