Remove NOTIMPLEMENTED calls from power_save_blocker_ozone
Remove NOTIMPLEMENTED calls from power_save_blocker_ozone

Chromecast uses this implementation, and it does what we need, but the
log errors are just unwanted noise.  ChromeOS Ozone already has its own
separate implementation in power_save_blocker_chromeos.cc.

BUG=

Review URL: https://codereview.chromium.org/1155543004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#332433}

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