renderer-mus: Plumb LocalSurfaceId into RenderWidgetCompositor

If there is a RendererWindowTreeClient (Chrome is running in Mus-WS) then
plumb the LocalSurfaceId out to RenderWidgetCompositor for surface
synchronization.

BUG=672962

Review-Url: https://codereview.chromium.org/2778933002
Cr-Commit-Position: refs/heads/master@{#460268}
1 file changed