weblayer: bump skew allowed by 1

This is necessary as embedders are pulling from canary, not stable,
which makes for a much smaller skew.

BUG=none
TEST=none

Change-Id: I28bc2aac2038fb5757c60ee5251cb281ea10cdd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2450389Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813783}

weblayer/browser/java/org/chromium/weblayer_private/interfaces/WebLayerVersionConstants.java

@@ -15,5 +15,5 @@ public interface WebLayerVersionConstants {
      *
      * @see WebLayer#isAvailable()
      */
-    int MAX_SKEW = 3;
+    int MAX_SKEW = 4;
 }