Add GL_CHROMIUM_screen_space_antialiasing to support alternative AA

MSAA is very expensive on some platforms. We introduce extention
GL_CHROMIUM_screen_space_antialiasing to support other antialiasing
approach. It will perform antialiasing to the color attachments of
the currently bound draw framebuffer. As an example, we implement it
using GL_INTEL_framebuffer_CMAA which results in similar quality of
MSAA at better performance.

The blink side change is in below link:
https://codereview.chromium.org/1301923002

BUG=524285

Review URL: https://codereview.chromium.org/1298523003

Cr-Commit-Position: refs/heads/master@{#348412}


CrOS-Libchrome-Original-Commit: f23471c866d7d3334d61538eb738d494542b5cac
2 files changed
tree: e113b9ff9f3966de0819376829894aa4448840eb
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/