Don't discard framebuffer on Windows.
Don't discard framebuffer on Windows.

On non-tiling GPUs (essentially all windows machines that can run Chrome) discarding the framebuffer doesn't actually help performance. It can also cost power, as the discard can cause a flush in the intel driver, and for security the command buffer forces a clear of the framebuffer before using it (though that seems pretty cheap in practice). Overall, turning this off reduces power when playing a fullscreen h.264 1080p video from 5.0W to 4.9W in my testing.

BUG=570897,548231

Review URL: https://codereview.chromium.org/1571503002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#368513}

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