Upstream: Renderers are running in WebAPKs.

chrome/android/webapk/libs/common/src/org/chromium/webapk/lib/common/WebApkSandboxedProcessService.java

+// Copyright 2016 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.webapk.lib.common;
+
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.os.IBinder;
+import android.util.Log;
+
+import java.lang.reflect.Method;
+
+/**
+ * Child process service hosted by WebAPKs. This class uses Chrome's ClassLoader to create a
+ * {@link ChildProcessServiceImpl} object which loads Chrome's native libraries, initializes JNI
+ * and creates the renderer.
+ */
+public class WebApkSandboxedProcessService extends Service {
+    private static final String CHILD_PROCESS_SERVICE_IMPL_CLASS_NAME =
+            "org.chromium.content.app.ChildProcessServiceImpl";
+    private static final String TAG = "cr_WebApkSandboxedProcessService";
+
+    private Class<?> mChildProcessServiceImplClass;
+    private Object mChildProcessServiceImplInstance;

[Maria, 2016/06/17 17:09:24]

final on both objects above?

[Xi Han, 2016/06/17 18:35:19]

These two objects are initialized in onCreate(), not in the constructor. The
WebApkSandboxedProcessService extends Service, therefore all the logic are
implemented onCreate().

+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+
+        try {
+            Context hostBrowserContext =
+                    WebApkUtils.getHostBrowserContext(getApplicationContext());
+            ClassLoader classLoader = hostBrowserContext.getClassLoader();
+            mChildProcessServiceImplClass =
+                    classLoader.loadClass(CHILD_PROCESS_SERVICE_IMPL_CLASS_NAME);

[Maria, 2016/06/17 17:09:24]

Do we need all this reflection here because we want to use a different class
loader?

[Xi Han, 2016/06/17 18:35:19]

We only use Chrome's class loader to load ChildProcessServiceImpl class, not to
replace the WebAPK's class loader. So I think these reflection are still
necessary. Does it answer your question?

+            mChildProcessServiceImplInstance = mChildProcessServiceImplClass.newInstance();
+
+            Method createMethod = mChildProcessServiceImplClass.getMethod("create",
+                    Context.class, Context.class);
+            createMethod.invoke(mChildProcessServiceImplInstance, getApplicationContext(),
+                    hostBrowserContext);
+        } catch (Exception e) {
+            Log.d(TAG, "Unable to create a ChildProcessServiceImpl for the WebAPK.");
+            e.printStackTrace();

[Maria, 2016/06/17 17:09:24]

you can pass e as the third parameter to log and it will then print the
stacktrace.

I would suggest logging at a lower verbocity level for something like this where
failures are not expected.

[Xi Han, 2016/06/17 18:35:19]

Good catch, thanks!

+        }
+    }
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        // We call stopSelf() to request that this service be stopped as soon as the client
+        // unbinds. Otherwise the system may keep it around and available for a reconnect. The
+        // child processes do not currently support reconnect; they must be initialized from
+        // scratch every time.
+        stopSelf();
+        try {
+            Method bindMethod = mChildProcessServiceImplClass.getMethod(
+                    "bind", Intent.class);
+            return (IBinder) bindMethod.invoke(mChildProcessServiceImplInstance, intent);
+        } catch (Exception e) {
+            Log.d(TAG, "Unable to bind to the WebApkSandboxedProcessService.");
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        try {
+            Method destroyMethod = mChildProcessServiceImplClass.getMethod("destroy");
+            destroyMethod.invoke(mChildProcessServiceImplInstance);
+        } catch (Exception e) {
+            Log.d(TAG, "Unable to destroy the WebApkSandboxedProcessService.");
+            e.printStackTrace();
+        }
+    }
+}