WebView: Require charging for variations seed download

This follows the advice of go/power-analysis (internal document). The
download frequency is capped at 1/day anyway, so this shouldn't have
much effect on seed freshness.

BUG=733857

Change-Id: Ifceecf6877542af317ea08128af9bdeb5c6fb991
Reviewed-on: https://chromium-review.googlesource.com/1066801Reviewed-by: Changwan Ryu <changwan@chromium.org>
Commit-Queue: Paul Miller <paulmiller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560209}

android_webview/java/src/org/chromium/android_webview/services/AwVariationsSeedFetcher.java

@@ -100,9 +100,11 @@ public class AwVariationsSeedFetcher extends JobService {
 
         ComponentName thisComponent = new ComponentName(
                 ContextUtils.getApplicationContext(), AwVariationsSeedFetcher.class);
-        JobInfo.Builder builder = new JobInfo.Builder(JOB_ID, thisComponent);
-        builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY);
-        if (scheduler.schedule(builder.build()) != JobScheduler.RESULT_SUCCESS) {
+        JobInfo job = new JobInfo.Builder(JOB_ID, thisComponent)
+                .setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY)
+                .setRequiresCharging(true)
+                .build();
+        if (scheduler.schedule(job) != JobScheduler.RESULT_SUCCESS) {
             Log.e(TAG, "Failed to schedule job");
         }
     }

android_webview/javatests/src/org/chromium/android_webview/test/AwVariationsSeedFetcherTest.java

@@ -96,6 +96,8 @@ public class AwVariationsSeedFetcherTest {
             Assert.assertEquals("Job scheduled with wrong ID", JOB_ID, job.getId());
             Assert.assertEquals("Job scheduled with wrong network type",
                     JobInfo.NETWORK_TYPE_ANY, job.getNetworkType());
+            Assert.assertTrue("Job scheduled without charging requirement",
+                    job.isRequireCharging());
             mJob = job;
             return JobScheduler.RESULT_SUCCESS;
         }
@@ -191,7 +193,9 @@ public class AwVariationsSeedFetcherTest {
             ComponentName component = new ComponentName(
                     ContextUtils.getApplicationContext(), AwVariationsSeedFetcher.class);
             JobInfo job = new JobInfo.Builder(JOB_ID, component)
-                    .setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY).build();
+                    .setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY)
+                    .setRequiresCharging(true)
+                    .build();
             mScheduler.schedule(job);
             AwVariationsSeedFetcher.scheduleIfNeeded();
             // Check that our job object hasn't been replaced (meaning that scheduleIfNeeded didn't