[WebLayer] Fix crash when accessing null splitNames

This was introduced in http://crrev.com/c/2623118 but will only show up
in non-bundle builds.

Bug: 1105096
Change-Id: Iadcdae745df6a54fe1d969ada113fafb6c25bce0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2627140
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Auto-Submit: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843058}

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -937,6 +937,10 @@ public final class WebLayerImpl extends IWebLayer.Stub {
         PostTask.postTask(TaskTraits.BEST_EFFORT_MAY_BLOCK, () -> {
             ApplicationInfo appInfo = packageInfo.applicationInfo;
             String[] splitNames = ApiHelperForO.getSplitNames(appInfo);
+            if (splitNames == null) {
+                return;
+            }
+
             for (int i = 0; i < splitNames.length; i++) {
                 String splitName = splitNames[i];
                 // WebLayer depends on the "weblayer" split and "chrome" split (if running in