Add a chrome://webapks page.

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
index 9ee9075312b3efe99ab0b31b6abc1f194e7ce46e..804ee098d45c096e9cdabb14832dde75c22d630d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
@@ -5,7 +5,9 @@
 package org.chromium.chrome.browser.webapps;
 
 import android.content.Context;
+import android.content.Intent;
 import android.content.SharedPreferences;
+import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.AsyncTask;
@@ -13,6 +15,7 @@ import android.os.AsyncTask;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
+import org.chromium.chrome.browser.ShortcutHelper;
 import org.chromium.chrome.browser.browsing_data.UrlFilter;
 import org.chromium.chrome.browser.browsing_data.UrlFilterBridge;
 
@@ -42,6 +45,7 @@ public class WebappRegistry {
     static final String REGISTRY_FILE_NAME = "webapp_registry";
     static final String KEY_WEBAPP_SET = "webapp_set";
     static final String KEY_LAST_CLEANUP = "last_cleanup";
+    static final String WEB_APK_PACKAGE_NAME_PREFIX = "org.chromium.webapk";

[Xi Han, 2017/01/13 15:50:15]

You can use WebApkConstants#WEBAPK_PACKAGE_PREFIX

[gonzalon, 2017/01/13 20:24:39]

Done.

 
     /** Represents a period of 4 weeks in milliseconds */
     static final long FULL_CLEANUP_DURATION = TimeUnit.DAYS.toMillis(4L * 7L);
@@ -168,6 +172,34 @@ public class WebappRegistry {
     }
 
     /**
+     * Fetches the information of all Web APKs installed on the device and returns them to the
+     * caller using a callback.
+     *
+     * @param webapkInfoCallback Callback to be called with each Web APK found on the device.
+     */
+    @CalledByNative
+    static void listWebAPKs(WebapkInfoCallback webapkInfoCallback) {

[Xi Han, 2017/01/13 15:50:15]

Usually we put helper functions in ShorcutHelper. WebAppRegister is used to
register WebApp or WebAPK in the shared preference, it might not be the right
place.

[gonzalon, 2017/01/13 20:24:38]

Sounds good! Sorry, I just didn't know where to put it, there are a lot of
classes! Moved it there.

+        PackageManager packageManager = ContextUtils.getApplicationContext().getPackageManager();
+        for (PackageInfo packageInfo : packageManager.getInstalledPackages(0)) {
+            if (packageInfo.packageName.startsWith(WEB_APK_PACKAGE_NAME_PREFIX)) {

[pkotwicz, 2017/01/13 16:00:54]

Perhaps, you can call WebApkValidator#isValidWebApk() here. Note that
WebApkValidator#isValidWebApk() is currently private

[gonzalon, 2017/01/13 20:24:38]

SG, done

+                Intent intent = new Intent();
+                intent.putExtra(ShortcutHelper.EXTRA_WEBAPK_PACKAGE_NAME, packageInfo.packageName);
+                // Any URL is fine, since we're only doing this to get info on the Web APK.
+                intent.putExtra(ShortcutHelper.EXTRA_URL, "https://www.google.com/");

[hartmanng, 2017/01/13 15:40:21]

I don't understand why a URL is required at all, could you explain this a bit
more?

[gonzalon, 2017/01/13 20:24:38]

As Xi mentioned in the other comment, it was an attempt to reuse the code that
was already there, but I'll change it to the approach she described, which will
make this code clearer and won't require this URL anymore.

+                WebApkInfo webApkInfo = WebApkInfo.create(intent);

[Xi Han, 2017/01/13 15:50:15]

I understand you want to reuse the code, but it is weird to create a WebApkInfo
which is barely used. My suggestion is:
1) Make WebApkInfo#extractWebApkMetaData() public, so call it to get the
metadata info.
2) Use IntentUtils.safeGet...() to get the meta data needed:
   String shortName = IntentUtils.safeGetString(bundle,
WebApkMetaDataKeys.SHORT_NAME);
3) I remembered that we also want to have the icon, don't we? You can follow
this example to get the icon:
  int iconId = IntentUtils.safeGetInt(bundle, WebApkMetaDataKeys.ICON_ID, 0);
  Bitmap icon = decodeImageResource(webApkPackageName, iconId);
  Note: make decodeImageResource as public too.

[pkotwicz, 2017/01/13 16:00:54]

Can you create a new version of WebApkInfo#create() which takes in just:
- The WebAPK package name
- The URL
- The source

I would use an empty URL instead of "https://www.google.com/" (and as Glenn
mentioned add a comment why the URL is empty instead of null)

[pkotwicz, 2017/01/13 16:23:19]

I had code elsewhere which looked like what you are suggesting and Dominick did
not like it. I am not very concerned about not really using WebApkInfo because
this is a function which will not be called often

[Xi Han, 2017/01/13 17:52:43]

That is fine, we can defer it to Dominick:)

+                if (webApkInfo != null) {
+                    String appName = webApkInfo.shortName();
+                    String packageName = webApkInfo.webApkPackageName();
+                    int shellApkVersion = webApkInfo.shellApkVersion();
+                    int versionCode = packageInfo.versionCode;
+                    webapkInfoCallback.onWebApkFound(
+                            appName, packageName, shellApkVersion, versionCode);

[pkotwicz, 2017/01/13 16:23:19]

Nit: Inline lines 191 - 194

[gonzalon, 2017/01/13 20:24:38]

Done.

+                }
+            }
+        }
+    }
+
+    /**
      * Deletes the data for all "old" web apps, as well as all WebAPKs that have been uninstalled in
      * the last month. "Old" web apps have not been opened by the user in the last 3 months, or have
      * had their last used time set to 0 by the user clearing their history. Cleanup is run, at