Introduce background Download process to android

content/public/android/java/src/org/chromium/content/app/DownloadProcessService.java

+// Copyright 2015 The Chromium Authors. All rights reserved.

[no sievers, 2016/02/03 22:46:52]

nit: 2016

[qinmin, 2016/02/03 23:37:36]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.content.app;
+
+import android.annotation.SuppressLint;
+import android.app.Notification;
+import android.content.Intent;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.IBinder;
+import android.os.RemoteException;
+
+import org.chromium.base.Log;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.content.browser.ChildProcessConstants;
+import org.chromium.content.common.IChildProcessCallback;
+
+/**
+ * Background download process for handling all transferable downloads.
+ */
+@JNINamespace("content")
+public class DownloadProcessService extends ChildProcessService {
+    private static final String TAG = "DownloadProcess";
+    private long mClientContext;
+    private IChildProcessCallback mCallback;
+    private int mDownloadCount;
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        // TODO(qinmin): Use the first pending download as notification, or
+        // get a more proper notification for this.
+        startForeground(ChildProcessConstants.DOWNLOAD_PROCESS_NOTIFICATION_ID, new Notification());
+    }
+
+    @Override
+    @SuppressLint("NewApi")
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        assert Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2;
+        initializeParams(intent);
+        Bundle bundle = intent.getExtras();
+        if (bundle != null) {
+            IBinder binder = bundle.getBinder(ChildProcessConstants.EXTRA_CHILD_PROCESS_CALLBACK);
+            mCallback = IChildProcessCallback.Stub.asInterface(binder);
+            getServiceInfo(bundle);
+        }
+        return START_STICKY;
+    }
+
+    /**
+     * Will be called by the native side when a download starts or is rejected.
+     */

[no sievers, 2016/02/03 22:46:52]

@CalledByNative

[qinmin, 2016/02/03 23:37:36]

added @CalledByNative in the comments. This is not yet called, and adding
@CalledByNative will cause jni generator to generate the stub in _jni file. 

+    private void onDownloadStarted(boolean started, int downloadId) {
+        if (mCallback != null) {
+            try {
+                mCallback.onDownloadStarted(started, downloadId);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Unable to callback the browser process.", e);
+            }
+        }
+        if (started) mDownloadCount++;
+    }
+
+    /**
+     * Will be called by the native side when a download completes.
+     */
+    private void onDownloadCompleted(boolean success) {

[no sievers, 2016/02/03 22:46:52]

@CalledByNative

[qinmin, 2016/02/03 23:37:36]

same as above

+        mDownloadCount--;
+        if (mDownloadCount == 0) stopSelf();
+    }
+}