Fix null crash in CustomTabsConnection

Turns out the array object could be null in some cases.
This CL adds a check for null array object and returns
earlier in case it's null.

Bug: 1084755
Change-Id: I9cb7f5f5e2b4fb724dca76bad3e0c558dc6b1d64
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2209514
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Cr-Commit-Position: refs/heads/master@{#770792}

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

@@ -603,9 +603,9 @@ public class CustomTabsConnection {
         PackageManager pm = context.getApplicationContext().getPackageManager();
         String[] packages = pm.getPackagesForUid(uid);
 
-        PostTask.postTask(UiThreadTaskTraits.DEFAULT, () -> {
-            if (packages.length == 0) return;
+        if (packages == null || packages.length == 0) return;
 
+        PostTask.postTask(UiThreadTaskTraits.DEFAULT, () -> {
             List<String> urlsList = new ArrayList<String>();
             if (url != null) urlsList.add(url);