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- Show edit and delete buttons for screenshot preview notification.
- Show only an edit button for video preview notification.

# Testing
- Screen recording shows expected buttons in preview notification
for image and video, and correct behaviors when pressing each button.
https://drive.google.com/file/d/10KUoHfGgNk3hzZACNz2WOSZmkYGY4Cl9/view?usp=sharing

Bug: 1136666
Change-Id: Ia6efe6ce5862dc2be1163b994f5ef74966ee6c47
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2488365
Commit-Queue: Cattalyya Nuengsigkapian <cattalyya@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819915}