GitLab

Blink has some logic for rendering a custom error page if a navigation
fails due to an HTTP error and the response body is empty, so the user
does not simply seen a blank page on error.

https://crrev.com/796508 added a number of `CHECK`s to assert that
navigations always commit. However, it incorrectly trips in the case of
a navigation to a media document that results in an HTTP error since:

1. Media documents synchronously complete loading while handling the
   `CommitNavigation` IPC.
2. When loading is complete, //content checks if the navigation
   resulted in an HTTP error—and if so, whether the response body was
   empty.
3. If both of those conditions are true, //content synthesises a custom
   error page and calls `blink::WebNavigationControl::CommitNavigation`.

Step 3 currently asserts that no commit is in progress, which is not
true in the case of media documents. This CL is intended to be a small
and mergeable patch and simply updates the error page handling in
`RunScriptsAtDocumentReady()` to better handle reentrant commits.

Bug: 1127837
Change-Id: Ied6ce00e10ff8e3b75306e97dba3d28fcd2e4c6f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2430769
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811593}