Move existing renderer from PepperView to PepperVideoRenderer2D.

A cleanup change that:
1. Adds PepperViewRenderer interface,
2. Moves existing renderer from PepperView to PepperVideoRenderer2D.

This will allow to implement PepperVideoRenderer3D and fallback to
software rendering when Graphics3D interface is not available.

BUG=414923

Review URL: https://codereview.chromium.org/806293003

Cr-Commit-Position: refs/heads/master@{#309146}
14 files changed