Add a chrome://webapks page.

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;
@@ skipping 51 matching lines @@
 
     /**
      * @param context The context to use to check whether WebAPK is valid.
      * @param infos The ResolveInfos to search.
      * @return Package name of the ResolveInfo which corresponds to a WebAPK. Null if none of the
      * ResolveInfos corresponds to a WebAPK.
      */
     public static String findWebApkPackage(Context context, List<ResolveInfo> infos) {
         for (ResolveInfo info : infos) {
             if (info.activityInfo != null
-                    && info.activityInfo.packageName.startsWith(WEBAPK_PACKAGE_PREFIX)
                     && isValidWebApk(context, info.activityInfo.packageName)) {
                 return info.activityInfo.packageName;
             }
         }
         return null;
     }
 
     /**
      * Returns whether the provided WebAPK is installed and passes signature checks.
      * @param context A context
      * @param webappPackageName The package name to check
      * @return true iff the WebAPK is installed and passes security checks
      */
-    private static boolean isValidWebApk(Context context, String webappPackageName) {
+    public static boolean isValidWebApk(Context context, String webappPackageName) {
         if (sExpectedSignature == null) {
             Log.wtf(TAG, "WebApk validation failure - expected signature not set."
                     + "missing call to WebApkValidator.initWithBrowserHostSignature");
         }
+        if (!webappPackageName.startsWith(WEBAPK_PACKAGE_PREFIX)) {
+            return false;
+        }
         // check signature
         PackageInfo packageInfo = null;
         try {
             packageInfo = context.getPackageManager().getPackageInfo(webappPackageName,
                     PackageManager.GET_SIGNATURES);
         } catch (NameNotFoundException e) {
             e.printStackTrace();
             Log.d(TAG, "WebApk not found");
             return false;
         }
@@ skipping 16 matching lines @@
      * with for the current host.
      * @param expectedSignature
      */
     public static void initWithBrowserHostSignature(byte[] expectedSignature) {
         if (sExpectedSignature != null) {
             return;
         }
         sExpectedSignature = Arrays.copyOf(expectedSignature, expectedSignature.length);
     }
 }