Surface synchronization: Simplify OOPIF and BrowserPlugin

With CL 669444, if a primary SurfaceInfo is specified on a layer
and no fallback is specified, then SurfaceAggregator will use an
embedder provided default background color to fill the space of the
primary Surface if the primary Surface is unavailable at surface
aggregation time.

Previously, SurfaceAggregator reported this case as an error and
logged UMA for a missing surface. Given this state is no longer considered
an error, there is room for simplifying code in BrowserPlugin and
RenderFrameProxy.

The default background color is set to SK_ColorTRANSPARENT to match the
current behavior. The primary surface is set as soon as it can be and
doesn't wait for the first fallback surface to become available.

Bug: 672962
Change-Id: I0ec6153356978e8994b50bfd4a024369e6f320d7
Reviewed-on: https://chromium-review.googlesource.com/686354
Commit-Queue: Fady Samuel <[email protected]>
Reviewed-by: Antoine Labour <[email protected]>
Cr-Commit-Position: refs/heads/master@{#504869}
6 files changed