I am attempting to bisect this. It's slow because bisect-builds.py doesn't work (crashes on startup in v8 trying to load a "snapshot") and there is a large range where chrome --mash crashes on startup due to  issue 804508 . I hope to have results in an hour or so.

samans, can you figure out how to revert your CL?

This is caused by the commit below. I cannot cleanly revert due to subsequent changes in RenderWidgetHostViewAura and some Mac files. I have attempted a manual revert in https://chromium-review.googlesource.com/#/c/chromium/src/+/895198 but I'm not sure if it's correct. Feel free to patch that in or land it if it looks right.

commit f7731345b34fd9f87ce5792f5f952f8e5cdfaac8
Author: Saman Sami <samans@chromium.org>
Date:   Wed Jan 24 22:18:44 2018 +0000

    Surface synchronization: Allocate new LocalSurfaceId on navigation
    
    In order to be able to tell the difference between the graphical output
    of the renderer before and after navigation, we should allocate a new
    LocalSurfaceId. Currently we rely on content_source_id to achieve this,
    but that is not compatible with Viz. When navigation happens, browser
    allocates a new id for the child and immediately embeds it. After 4
    seconds it drops the fallback SurfaceId if it was generated before
    navigation.
    
    TBR=lazyboy@chromium.org
    
    Bug:  695579 , 775030 , 777881 
    Change-Id: I8ae11dd3de2e8d6cc889ad31f94bdb0bb5f6a5d4
    Reviewed-on: https://chromium-review.googlesource.com/855256
    Commit-Queue: Saman Sami <samans@chromium.org>
    Reviewed-by: Fady Samuel <fsamuel@chromium.org>
    Reviewed-by: Saman Sami <samans@chromium.org>
    Reviewed-by: Ken Buchanan <kenrb@chromium.org>
    Reviewed-by: Antoine Labour <piman@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#531713}

I don't think this should be reverted because this impacts an about-to-be-finch tried Viz and impacts a large set of dependencies. I think we should fix Mash instead as that's a longer term project.

I've started looking into this. A revert is probably not necessary.

This is the same behavior that I'm seeing on Mac. Can we revert just the 2 lines that are blocking Mac development?

https://chromium-review.googlesource.com/c/chromium/src/+/894197

There is, I believe, a fix in flight for this. I don't think we can revert this patch easily. It should be fairly easy to fix this on Mac too.

Adding some commentary from my follow-on at https://chromium-review.googlesource.com/c/chromium/src/+/898544

When we resize, we have the following sequence of calls:
  RenderWidgetHostViewAura::WasResized calls (with no arguments)
  DelegatedFrameHost::WasResized which calls
  DelegatedFrameHostClient::DelegatedFrameHostDesiredSizeInDIP
    which is virtual and implemented as
  DelegatedFrameHostClientAura::DelegatedFrameHostDesiredSizeInDIP
    which then calls
  RenderWidgetHostViewAura to query the window bounds

The above patch has RenderWidgetHostViewAura::WasResized push the window bounds to DelegatedFrameHost::WasResized directly.

But, we will keep hitting this issue. Ultimately, whoever is responsible for allocating LocalSurfaceIds needs to have a "OnSurfaceChanged" notification that specifies the new (id,size,scale_factor) of the surface, and then DelegatedFrameHost (or its embedder) can subscribe to those notifications.

As it is, we're well on our way to a world where we sprinkle WasResized() calls all over in the hopes that we catch every instance where the surface id changes.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5a727b5474461d381bc5d49112926588e786302f

commit 5a727b5474461d381bc5d49112926588e786302f
Author: Saman Sami <samans@chromium.org>
Date: Fri Feb 02 22:42:05 2018

mus: Embed the new surface in WindowPortMus::AllocateLocalSurfaceId

Seems like we don't embed the LocalSurfaceId allocated in
WindowPortMus::AllocateLocalSurfaceId with --mash. Embed it.

Bug:  807448 
Change-Id: Id4c03c01d714de010a8306fc97bcd1a98dfaa3cb
Reviewed-on: https://chromium-review.googlesource.com/895926
Commit-Queue: Saman Sami <samans@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534176}
[modify] https://crrev.com/5a727b5474461d381bc5d49112926588e786302f/ui/aura/mus/client_surface_embedder.cc
[modify] https://crrev.com/5a727b5474461d381bc5d49112926588e786302f/ui/aura/mus/client_surface_embedder.h
[modify] https://crrev.com/5a727b5474461d381bc5d49112926588e786302f/ui/aura/mus/window_port_mus.cc
[modify] https://crrev.com/5a727b5474461d381bc5d49112926588e786302f/ui/aura/mus/window_port_mus_unittest.cc

I expect this issue to be fixed. If you're still seeing it please reopen the bug.

It works now, thanks!