[Background Sync] Revert changes to ChromeBackgroundService.

A recent CL added some logic based on a feature being enabled
in ChromeBackgroundService:
https://chromium-review.googlesource.com/c/chromium/src/+/1432840

However, since the native JNI library might not be loaded at this point,
the feature check can't be done -- it causes a crash.
This CL takes out logic to ChromeBackgroundService, to be re-introduced
when BackgroundTaskSchedulerForBackgroundSync feature is enabled
everywhere.

Bug: 924490, 932468
Change-Id: Ia1930c76a36e88a2a2bc53be96582123118ddc97
Reviewed-on: https://chromium-review.googlesource.com/c/1474655
Commit-Queue: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632720}

chrome/android/java/src/org/chromium/chrome/browser/ChromeBackgroundService.java

@@ -14,7 +14,6 @@ import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.library_loader.ProcessInitException;
-import org.chromium.chrome.browser.background_sync.BackgroundSyncBackgroundTaskScheduler;
 import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
 import org.chromium.chrome.browser.init.ServiceManagerStartupUtils;
 import org.chromium.chrome.browser.ntp.snippets.SnippetsBridge;
@@ -71,14 +70,6 @@ public class ChromeBackgroundService extends GcmTaskService {
     }
 
     private void handleBackgroundSyncEvent(Context context, String tag) {
-        if (ChromeFeatureList.isEnabled(
-                    ChromeFeatureList.BACKGROUND_TASK_SCHEDULER_FOR_BACKGROUND_SYNC)) {
-            // If BackgroundTaskScheduler has been used to schedule a background
-            // task for Background Sync, we simply reschedule the existing task(s).
-            BackgroundSyncBackgroundTaskScheduler.getInstance().reschedule();
-            return;
-        }
-
         if (!BackgroundSyncLauncher.hasInstance()) {
             // Start the browser. The browser's BackgroundSyncManager (for the active profile) will
             // start, check the network, and run any necessary sync events. This task runs with a

chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackgroundServiceTest.java

@@ -23,8 +23,6 @@ import org.chromium.base.test.util.RetryOnFailure;
 import org.chromium.chrome.browser.ntp.snippets.SnippetsLauncher;
 import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 
-import java.util.HashMap;
-
 /**
  * Tests {@link ChromeBackgroundService}.
  */
@@ -80,13 +78,9 @@ public class ChromeBackgroundServiceTest {
 
     @Before
     public void setUp() throws Exception {
-        HashMap<String, Boolean> features = new HashMap<String, Boolean>();
-        features.put(ChromeFeatureList.BACKGROUND_TASK_SCHEDULER_FOR_BACKGROUND_SYNC, false);
-        ChromeFeatureList.setTestFeatures(features);
         BackgroundSyncLauncher.setGCMEnabled(false);
-        mSyncLauncher = BackgroundSyncLauncher.create();
-
         RecordHistogram.setDisabledForTests(true);
+        mSyncLauncher = BackgroundSyncLauncher.create();
         mSnippetsLauncher = SnippetsLauncher.create();
         mTaskService = new MockTaskService();
     }