switch to using SaveLayerFlags (SaveFlags are deprecated)
switch to using SaveLayerFlags (SaveFlags are deprecated)

prepares the way for https://codereview.chromium.org/1535993003

BUG=

Review URL: https://codereview.chromium.org/1537203002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#366288}

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