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FrameResourceFence was introduced in
https://chromium-review.googlesource.com/c/chromium/src/+/1600617 to
properly support display of video from GpuMemoryBuffers. Idea is that
DisplayResourceProvider will signal that a fence is needed
(https://cs.chromium.org/chromium/src/components/viz/service/display/display_resource_provider.cc?rcl=b42e627df3d2285cccb73e90ace0c96667a42652&l=514)
and later check if the fence has passed before deleting the resource
(https://cs.chromium.org/chromium/src/components/viz/service/display/display_resource_provider.cc?rcl=b42e627df3d2285cccb73e90ace0c96667a42652&l=657).

This CL does 2 things.

(1) Fixes a bug where we were previously signaling the fence in
    DisplayResourceProvider::LockForRead, when we shouldn't
    have. We should only signal the fence once it is safe to delete.

(2) Only sets |on_finished_callback| if some resource needed a readlock
    fence. This microoptimization improves performance on
    RendererPerfTest.

Bug: 974359
Change-Id: If72985b566a6082382c0baf6887408fa42bb9299
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1775100Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Jonathan Backer <backer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691625}