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These have all been enabled by default client-side or removed for some time:
- PWAFullCodeCache in Chrome 67
- ServiceWorkerNavigationPreload in Chrome 59
- ServiceWorkerScriptFullCodeCache in Chrome 67
- ServiceWorkerScriptStreaming in Chrome 64
- SpeculativeLaunchServiceWorker was removed

Bug: 661071, 683037, 768705, 640132
Change-Id: Id218f3882273063db7e4c358cac956ca54f362d8
Reviewed-on: https://chromium-review.googlesource.com/1147895Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577711}