Create //components/viz/frame_sinks and move code.

Move all of the existing code for what used to be called
DisplayCompositor and is now MojoFrameSinkManager from various places to
a single target under src/components/viz/. This is the chunk of code that
both mus and non-mus will use to implement the FrameSinkManager
interface.

BUG=664547

Review-Url: https://codereview.chromium.org/2795823003
Cr-Commit-Position: refs/heads/master@{#462633}
20 files changed