GitLab

This debugging page hasn't been used by the Sync team in a while, so
this CL removes it. Consequently, SyncInternalsMessageHandler no longer
needs to implement TypeDebugInfoObserver. This unblocks the removal of
such observer interface in future CLs (chrome://sync-internals was its
last "real" implementation).

Bug: 1102849
Change-Id: Idb2ed8af56c9133a884b79ccfa131dce630fa1bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2465743Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Victor Vianna <victorvianna@google.com>
Cr-Commit-Position: refs/heads/master@{#816131}