Fix some broken github sample links in app docs

Some sample links in app docs breaks since github code tree
has been updated, so they should track the new correct URL.
Although webintents has been deprecated, but broken links seems
not well, so I use the last tree where the code exists, and use
the blod deprecated mark to remind readers never use it.

BUG=465401

Review URL: https://codereview.chromium.org/991973002

Cr-Commit-Position: refs/heads/master@{#320192}
6 files changed