[Android] Native initialization task for BackgroundTaskScheduler

chrome/android/java/src/org/chromium/chrome/browser/background_task_scheduler/NativeBackgroundTask.java

+// 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.
+
+package org.chromium.chrome.browser.background_task_scheduler;
+
+import android.content.Context;
+
+import org.chromium.base.Log;
+import org.chromium.base.library_loader.LibraryProcessType;
+import org.chromium.base.library_loader.ProcessInitException;
+import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
+import org.chromium.components.background_task_scheduler.BackgroundTask;
+import org.chromium.components.background_task_scheduler.TaskParameters;
+import org.chromium.content.browser.BrowserStartupController;
+
+/**
+ * Base class implementing {@link BackgroundTask} that adds native initialization, ensuring that
+ * tasks are run after Chrome is successfully started.
+ * Background tasks that require native parts of browser to be started should extend this class
+ * instead of implementing the interface directly. {@link #onStartTaskWithNative(Context,
+ * TaskParameters, TaskFinishedCallback)} method should be implemented instead of {@link
+ * #onStartTask(Context, TaskParameters, TaskFinishedCallback)}.
+ */
+public abstract class NativeBackgroundTask implements BackgroundTask {

[nyquist, 2017/04/18 22:48:43]

How would you feel about writing a test to ensure that when the subclass gets a
call to onStartTaskWithNative, it does in fact always have native?

If you want to run on the host, maybe just create a shadow for
BrowserStartupController and ChromeBrowserInitializer?

[fgorski, 2017/04/21 18:45:43]

Here is what I thought 3 hours ago: hold my beer...

It's done now, but you know... lot's of tears :)

+    private static final String TAG = "BTS_NativeBkgrdTask";
+
+    protected NativeBackgroundTask() {}
+
+    @Override
+    public final boolean onStartTask(
+            Context context, TaskParameters taskParameters, TaskFinishedCallback callback) {
+        ensureNativeInitialized(context);
+        return onStartTaskWithNative(context, taskParameters, callback);
+    }
+
+    /**
+     * Method that should be implemented in derived classes to provide implementation of {@link
+     * BackgroundTask#onStartTask(Context, TaskParameters, TaskFinishedCallback)}.
+     */
+    protected abstract boolean onStartTaskWithNative(
+            Context context, TaskParameters taskParameters, TaskFinishedCallback callback);
+
+    /**
+     * Method that ensure that native parts of Chrome are initialized, before further work can be
+     * done. If native part is initialized this method does nothing.
+     */
+    protected void ensureNativeInitialized(Context context) {

[nyquist, 2017/04/18 22:48:44]

Nit:  I think you want @SuppressFBWarnings("DM_EXIT") here.

[fgorski, 2017/04/21 18:45:43]

Actually I thought of a different approach, in which we return success status.
If we are not able to start native, onStartTask will return without calling
implementation further. This means no sad surprises from the component and no
exception while invoked from the background. WDYT?

+        if (BrowserStartupController.get(LibraryProcessType.PROCESS_BROWSER)
+                        .isStartupSuccessfullyCompleted()) {
+            return;
+        }
+
+        try {
+            ChromeBrowserInitializer.getInstance(context).handleSynchronousStartup();
+        } catch (ProcessInitException e) {
+            Log.e(TAG, "ProcessInitException while starting the browser process.");
+            // Since the library failed to initialize nothing in the application can work, so kill
+            // the whole application not just the activity.
+            System.exit(-1);
+        }
+    }
+}