Upstream: Extract "WebAPK service" implementation from Chrome APK

chrome/android/webapk/libs/common/src/org/chromium/webapk/lib/common/WebApkUtils.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.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.os.Bundle;
+
+/**
+ * Contains utility methods for interacting with WebAPKs.
+ */
+public class WebApkUtils {
+
+    /**
+     * Caches the value read from Application Metadata which specifies the host browser's package
+     * name.
+     */
+    private static String sHostPackage;
+
+    /**
+     * Returns a Context for the host browser that was specified when building the WebAPK.
+     * @param context A context.
+     * @return The remote context. Returns null on an error.
+     */
+    public static Context getHostBrowserContext(Context context) {
+        try {
+            String hostPackage = getHostBrowserPackageName(context);
+            return context.getApplicationContext().createPackageContext(
+                            hostPackage,
+                            Context.CONTEXT_IGNORE_SECURITY | Context.CONTEXT_INCLUDE_CODE);
+        } catch (NameNotFoundException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    /**
+     * Returns the package name for the host browser that was specified when building the WebAPK.
+     * @param context A context.
+     * @return The package name. Returns null on an error.
+     */
+    public static String getHostBrowserPackageName(Context context) {
+        if (sHostPackage != null) return sHostPackage;
+        String hostPackage = null;
+        try {
+            ApplicationInfo ai = context.getPackageManager().getApplicationInfo(
+                    context.getPackageName(), PackageManager.GET_META_DATA);
+            Bundle bundle = ai.metaData;
+            hostPackage = bundle.getString("runtimeHost");
+        } catch (NameNotFoundException e) {
+            e.printStackTrace();
+        }
+        // Set {@link sHostPackage} to a non-null value so that the value is computed only once.
+        sHostPackage = hostPackage != null ? hostPackage : "";
+        return sHostPackage;
+    }
+}