[roll third_party/pigweed] pw_web: Json Log Source example

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/169176

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 1961c9c8ef71c4f..d5843fe323e42c8
Roller-URL: https://ci.chromium.org/b/8771206606796444865
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I580c146c66fa232c6fe094977d65cd5ceef06277
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/169180
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 1961c9c..d5843fe 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 1961c9c8ef71c4fec09b34a96f86bf2b9456fe38
+Subproject commit d5843fe323e42c8865a23a508daba82f392bc35f