[Android]: Hide add-to-homescreen app menu item when WebAPK is installed

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.LinkedList;
 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;
 
     /**
      * 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.
      * @return Package name of WebAPK which can handle the URL. Null if the url should not be
      * handled by a WebAPK.
      */
     public static String queryWebApkPackage(Context context, String url) {
+        return findWebApkPackage(context, resolveInfosForUrl(context, url));
+    }
+
+    /**
+     * 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: This can fail if multiple WebAPKs can match the supplied url.

[nyquist, 2017/02/28 07:04:19]

What does fail mean in this scenario? From the code it looks like we will just
be returning the first one?

[gonzalon, 2017/02/28 16:12:24]

Yes, I added a clarification on the comment about the behavior.

+     *
+     * @param context The application context.
+     * @param url The url to check.

[nyquist, 2017/02/28 07:04:19]

Nit: Comments are written in normal English, so URL should be all uppercase. I
would be OK with |url| though, if you want to refer to the URL parameter
specifically. Update the rest of the comment to URL too.

[gonzalon, 2017/02/28 16:12:24]

Done.

+     * @return Resolve Info of a WebAPK which can handle the URL. Null if the url should not be
+     * handled by a WebAPK.
+     */
+    public static ResolveInfo queryResolveInfo(Context context, String url) {
+        return findResolveInfo(context, resolveInfosForUrl(context, url));
+    }
+
+    /**
+     * Fetches the list of resolve infos from the PackageManager that can handle the URL.

[nyquist, 2017/02/28 07:04:19]

{@link ResolveInfo}s

[gonzalon, 2017/02/28 16:12:24]

Done.

+     *
+     * @param context The application context.
+     * @param url The url to check.
+     * @return The list of resolve infos found that can handle the URL.
+     */
+    private static List<ResolveInfo> resolveInfosForUrl(Context context, String url) {

[nyquist, 2017/02/28 07:04:19]

Would you want to annotate this with @Nonnull and/or update the @return
statement?

[gonzalon, 2017/02/28 16:12:23]

Done.

         Intent intent;
         try {
             intent = Intent.parseUri(url, Intent.URI_INTENT_SCHEME);
         } catch (Exception e) {
-            return null;
+            return new LinkedList<>();
         }
 
         intent.addCategory(Intent.CATEGORY_BROWSABLE);
         intent.setComponent(null);
         Intent selector = intent.getSelector();
         if (selector != null) {
             selector.addCategory(Intent.CATEGORY_BROWSABLE);
             selector.setComponent(null);
         }
-
-        List<ResolveInfo> resolveInfos = context.getPackageManager().queryIntentActivities(
+        return context.getPackageManager().queryIntentActivities(
                 intent, PackageManager.GET_RESOLVED_FILTER);
-        return findWebApkPackage(context, resolveInfos);
     }
 
     /**
      * @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) {
+        ResolveInfo resolveInfo = findResolveInfo(context, infos);
+        if (resolveInfo != null) {
+            return resolveInfo.activityInfo.packageName;
+        }
+        return null;
+    }
+
+    /**
+     * @param context The context to use to check whether WebAPK is valid.
+     * @param infos The ResolveInfos to search.
+     * @return ResolveInfo which corresponds to a WebAPK. Null if none of the ResolveInfos
+     * corresponds to a WebAPK.
+     */
+    private static ResolveInfo findResolveInfo(Context context, List<ResolveInfo> infos) {
         for (ResolveInfo info : infos) {
             if (info.activityInfo != null
                     && isValidWebApk(context, info.activityInfo.packageName)) {
-                return info.activityInfo.packageName;
+                return info;
             }
         }
         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
      */
     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();

[nyquist, 2017/02/28 07:04:19]

While you're at it, could you pleas remove this line? If it's supposed to stay,
add it as the third param to the log-statement below.

[gonzalon, 2017/02/28 16:12:23]

Done.

             Log.d(TAG, "WebApk not found");
             return false;
         }
 
         final Signature[] arrSignatures = packageInfo.signatures;
         if (arrSignatures != null && arrSignatures.length == 2) {
             for (Signature signature : arrSignatures) {
                 if (Arrays.equals(sExpectedSignature, signature.toByteArray())) {
                     Log.d(TAG, "WebApk valid - signature match!");
                     return true;
                 }
             }
         }
         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 (sExpectedSignature != null) {
             return;
         }
         sExpectedSignature = Arrays.copyOf(expectedSignature, expectedSignature.length);
     }
 }