Add a chrome://webapks page.

chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java b/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
index 9bb166773ac1199ec993a12a54d29685cb851db7..a8cbfdd3eacae3eab951ed03e44fbcf867c4120f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
@@ -9,6 +9,7 @@ import android.app.ActivityManager;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.ResolveInfo;
@@ -22,6 +23,7 @@ import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.AsyncTask;
+import android.support.annotation.NonNull;
 import android.text.TextUtils;
 import android.util.Base64;
 
@@ -34,6 +36,7 @@ import org.chromium.base.annotations.CalledByNative;
 import org.chromium.blink_public.platform.WebDisplayMode;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.webapps.ChromeWebApkHost;
+import org.chromium.chrome.browser.webapps.WebApkInfo;
 import org.chromium.chrome.browser.webapps.WebappActivity;
 import org.chromium.chrome.browser.webapps.WebappAuthenticator;
 import org.chromium.chrome.browser.webapps.WebappDataStorage;
@@ -45,6 +48,7 @@ import org.chromium.ui.widget.Toast;
 import org.chromium.webapk.lib.client.WebApkValidator;
 
 import java.io.ByteArrayOutputStream;
+import java.util.LinkedList;
 import java.util.List;
 
 /**
@@ -648,5 +652,49 @@ public class ShortcutHelper {
         return null;
     }
 
+    /**
+     * Fetches the information of all WebAPKs installed on the device and returns them to the
+     * caller using a callback.
+     *
+     * @param callbackPointer Callback to be called with the information on the WebAPKs found.
+     */
+    @CalledByNative
+    public static void listWebApks(long callbackPointer) {
+        List<String> shortNames = new LinkedList<>();

[pkotwicz, 2017/01/18 02:08:20]

Can you explain why you chose a LinkedList instead of an ArrayList?

Miscellaneous trivia: The initial capacity of a java.util.ArrayList is 10

[gonzalon, 2017/01/18 15:29:32]

I only use ArrayList when I'm sure of the final size of the array or if I'm
going to be querying by index a lot. In this case, since there probably aren't
going to be many elements anyways, it's the same performance-wise to use one or
the other, so I can use ArrayList if you prefer.

+        List<String> packageNames = new LinkedList<>();
+        List<Integer> shellApkVersions = new LinkedList<>();
+        List<Integer> versionCodes = new LinkedList<>();
+
+        PackageManager packageManager = ContextUtils.getApplicationContext().getPackageManager();
+        for (PackageInfo packageInfo : packageManager.getInstalledPackages(0)) {
+            if (WebApkValidator.isValidWebApk(
+                        ContextUtils.getApplicationContext(), packageInfo.packageName)) {
+                // We need to pass in a non-null URL as second parameter to fetch all the
+                // information about the WebAPK.
+                WebApkInfo webApkInfo = WebApkInfo.create(packageInfo.packageName, "", 0);

[pkotwicz, 2017/01/18 02:08:20]

Nit: 0 -> ShortcutSource.UNKNOWN

[gonzalon, 2017/01/18 15:29:32]

Done.

+                if (webApkInfo != null) {
+                    shortNames.add(webApkInfo.shortName());
+                    packageNames.add(packageInfo.packageName);
+                    shellApkVersions.add(webApkInfo.shellApkVersion());
+                    versionCodes.add(packageInfo.versionCode);
+                }
+            }
+        }

[pkotwicz, 2017/01/18 02:08:20]

Nit: For the sake of clarity I would do:
String[] shortNamesArray = shortNames.toArray(new String[shortNames.size()]);

nativeOnWebApksFound(callbackPointer, shortNamesArray, ...);

This is equally correct and shorter:
String[] shortNamesArray = shortNames.toArray(new String[0]);

[gonzalon, 2017/01/18 15:29:32]

It's not exactly the same, if the size of the array is too small, a new one with
the correct size is instantiated. I guess the hit of wasting an array of size 1 
is negligible. Done. 

+        nativeOnWebApksFound(callbackPointer, shortNames.toArray(new String[shortNames.size()]),
+                packageNames.toArray(new String[packageNames.size()]),
+                integerListToIntArray(shellApkVersions), integerListToIntArray(versionCodes));
+    }
+
+    private static int[] integerListToIntArray(@NonNull List<Integer> list) {

[pkotwicz, 2017/01/18 02:08:20]

+agrieve@

Cool! I did not know about this annotation. Andrew is our local expert on all of
the build stuff

[gonzalon, 2017/01/18 15:29:32]

This annotation doesn't actually enforce the argument not to be null, but if you
try to pass a null value (or a value that might be null) to this function,
Android Studio will highlight it with a warning.

[agrieve, 2017/01/19 19:58:23]

Yep, would love to see more support annotations being added!

+        int[] array = new int[list.size()];
+        int i = 0;
+        for (Integer integer : list) {

[pkotwicz, 2017/01/18 02:08:20]

Nit: integer -> value

I'm not a fan of naming a variable |integer|

[gonzalon, 2017/01/18 15:29:32]

Done.

+            array[i++] = integer;
+        }
+        return array;
+    }
+
     private static native void nativeOnWebappDataStored(long callbackPointer);
+    private static native void nativeOnWebApksFound(long callbackPointer, String[] shortNames,
+            String[] packageName, int[] shellApkVersions, int[] versionCodes);
 }