Upstream: Initialize ChromeWebApkHost in WebappLaunchActivity.

chrome/android/webapk/libs/client/src/org/chromium/webapk/lib/client/WebApkValidator.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.client;
 
 import static org.chromium.webapk.lib.common.WebApkConstants.WEBAPK_PACKAGE_PREFIX;
 
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.ResolveInfo;
 import android.content.pm.Signature;
 import android.util.Log;
 
 import java.util.Arrays;
 import java.util.List;
 
 /**
  * Checks whether a URL belongs to a WebAPK, and whether a WebAPK is signed by the WebAPK Minting
  * Server.
  */
 public class WebApkValidator {
 
     private static final String TAG = "WebApkValidator";
     private static byte[] sExpectedSignature;
+    private static boolean sIsInitialized = false;
 
     /**
      * Queries the PackageManager to determine whether a WebAPK can handle the URL. Ignores
      * whether the user has selected a default handler for the URL and whether the default
      * handler is the WebAPK.
      *
      * NOTE(yfriedman): This can fail if multiple WebAPKs can match the supplied url.
      *
      * @param context The application context.
      * @param url The url to check.
@@ skipping 72 matching lines @@
         Log.d(TAG, "WebApk invalid");
         return false;
     }
 
     /**
      * Initializes the WebApkValidator with the expected signature that WebAPKs must be signed
      * with for the current host.
      * @param expectedSignature
      */
     public static void initWithBrowserHostSignature(byte[] expectedSignature) {
+        if (sIsInitialized) {

[pkotwicz, 2016/06/10 21:34:14]

Can we return if sExpectedSignature != null ?

[Xi Han, 2016/06/13 20:10:53]

Done.

+            return;
+        }
         sExpectedSignature = Arrays.copyOf(expectedSignature, expectedSignature.length);
+        sIsInitialized = true;
     }
 }