[android] Add JobScheduler-based BackgroundTaskScheduler.

components/background_task_scheduler/BUILD.gn

+# Copyright 2017 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.
+
+if (is_android) {
+  import("//build/config/android/config.gni")
+  import("//build/config/android/rules.gni")
+}
+
+# Convenience target for developers to build prod and test code.
+group("background_task_scheduler") {
+  testonly = true
+
+  if (is_android) {
+    deps = [
+      ":background_task_scheduler_java",
+      ":background_task_scheduler_javatests",
+    ]
+  }
+}
+
+if (is_android) {
+  android_library("background_task_scheduler_java") {
+    java_files = [
+      "android/java/src/org/chromium/components/background_task_scheduler/BackgroundTask.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskJobService.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskScheduler.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerDelegate.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerFactory.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/BundleToPersistableBundleConverter.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/TaskIds.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/TaskInfo.java",
+      "android/java/src/org/chromium/components/background_task_scheduler/TaskParameters.java",
+    ]
+
+    deps = [
+      "//base:base_java",
+      "//third_party/android_tools:android_support_annotations_java",
+    ]
+  }
+
+  android_library("background_task_scheduler_javatests") {
+    testonly = true
+
+    java_files = [
+      "android/javatests/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobServiceTest.java",
+      "android/javatests/src/org/chromium/components/background_task_scheduler/BundleToPersistableBundleConverterTest.java",
+    ]
+
+    deps = [
+      ":background_task_scheduler_java",
+      "//base:base_java",
+      "//base:base_java_test_support",
+      "//third_party/android_support_test_runner:runner_java",
+      "//third_party/junit",
+    ]
+  }
+}