[Extensions] Update web API cloberring for platform apps

Platform App clobbering for certain Web APIs was incomplete.  Make it more
complete.  See bug for more details.

BUG=585282

Review URL: https://codereview.chromium.org/1716513002

Cr-Commit-Position: refs/heads/master@{#376784}
(cherry picked from commit dc42ae208c2744f7fb144b2e396358a1fc34db87)

Review URL: https://codereview.chromium.org/1744623002 .

Cr-Commit-Position: refs/branch-heads/2623@{#523}
Cr-Branched-From: 92d77538a86529ca35f9220bd3cd512cbea1f086-refs/heads/master@{#369907}
8 files changed