I'd do this as a very last step. I'm not a huge fan of these suggestions but I also can't think of better names. Naming is hard.

SetFallbackLowerbound is probably a better name than SetOldestAcceptableFallback. I also agree that this can be left as the last step, although we're already at a stage that these names are meaningful.

I think we should eventually rename these because "fallback" is a misnomer at this point.

I considered calling them:

SetSurfaceRangeStart
SetSurfaceRangeEnd

but I think people would be confused about calling 

SetSurfaceRangeEnd all the time instead of Start...


Calling SetPrimarySurfaceId just SetSurfaceId makes it clear that this is the default API to use.


SetOldestAcceptableFallback actually sounds closer to the real behavior.

If I wasn't familiar with surfaces, I don't think I'd understand what a "FallbackLowerbound" is.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/98c52405920b2125d191aa84f81ed790334e774f

commit 98c52405920b2125d191aa84f81ed790334e774f
Author: Saman Sami <samans@chromium.org>
Date: Fri Oct 26 17:34:57 2018

Improve method names for updating surface ids in SurfaceLayer

Rename SetPrimarySurfaceId to SetSurfaceId to make it clear it is the
default API to use.
Rename SetFallbackSurfaceId to SetOldestAcceptableFallback to make it
clear that surfaces newer than the provided surface id can be shown.
Also rename the corresponding methods in ui::Layer.

TBR=mlamouri@chromium.org,flackr@chromium.org,sadrul@chromium.org

Bug:  861834 
Change-Id: I6c5b9d6b24cef790372d41b3b837ede3799a0ebd
Reviewed-on: https://chromium-review.googlesource.com/c/1301845
Commit-Queue: Saman Sami <samans@chromium.org>
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603134}
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/cc/layers/surface_layer.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/cc/layers/surface_layer.h
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/cc/layers/surface_layer_impl.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/cc/layers/surface_layer_unittest.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/browser/picture_in_picture/overlay_surface_embedder.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/browser/renderer_host/delegated_frame_host.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/renderer/browser_plugin/browser_plugin.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/renderer/child_frame_compositing_helper.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/renderer/child_frame_compositing_helper.h
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/renderer/child_frame_compositing_helper_unittest.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/content/renderer/render_frame_proxy.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/services/ws/client_root.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/third_party/blink/renderer/platform/graphics/surface_layer_bridge.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/android/delegated_frame_host_android.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/android/delegated_frame_host_android_unittest.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/aura/local/window_port_local.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/aura/mus/client_surface_embedder.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/aura/mus/client_surface_embedder.h
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/aura/mus/window_port_mus.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/aura/mus/window_port_mus_unittest.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/compositor/layer.cc
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/compositor/layer.h
[modify] https://crrev.com/98c52405920b2125d191aa84f81ed790334e774f/ui/compositor/layer_unittest.cc