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

components/cronet/android/api/src/org/chromium/net/ExperimentalCronetEngine.java

 // Copyright 2016 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.support.annotation.VisibleForTesting;
 
 import java.io.IOException;
 import java.net.Proxy;
@@ skipping 132 matching lines @@
          *
          * @param options JSON formatted experimental options.
          * @return the builder to facilitate chaining.
          */
         public Builder setExperimentalOptions(String options) {
             mBuilderDelegate.setExperimentalOptions(options);
             return this;
         }
 
         /**
+         * Sets the thread priority of Cronet's internal thread.
+         *
+         * @param priority the thread priority of Cronet's internal thread.
+         *        A Linux priority level, from -20 for highest scheduling
+         *        priority to 19 for lowest scheduling priority. For more
+         *        information on values, see
+         *        {@link android.os.Process#setThreadPriority(int, int)} and
+         *        {@link android.os.Process#THREAD_PRIORITY_DEFAULT
+         *        THREAD_PRIORITY_*} values.
+         * @return the builder to facilitate chaining.
+         */
+        public Builder setThreadPriority(int priority) {
+            mBuilderDelegate.setThreadPriority(priority);
+            return this;
+        }
+
+        /**
          * Returns delegate, only for testing.
          * @hide
          */
         @VisibleForTesting
         public ICronetEngineBuilder getBuilderDelegate() {
             return mBuilderDelegate;
         }
 
         // To support method chaining, override superclass methods to return an
         // instance of this class instead of the parent.
@@ skipping 248 matching lines @@
      * {@link #CONNECTION_METRIC_UNKNOWN} if the value is
      * unavailable. This must be called after
      * {@link Builder#enableNetworkQualityEstimator}, and will
      * throw an exception otherwise.
      * @return Estimate of the downstream throughput in kilobits per second.
      */
     public int getDownstreamThroughputKbps() {
         return CONNECTION_METRIC_UNKNOWN;
     }
 }