PRs closed in this release of flutter/plugins

From Thu Feb 21 20:22:00 2019 -0800 to Wed May 1 16:56:00 2019 -0700

721 [google_sign_in]Fix filename in google_sign_in docs, which leads to crash (bugfix, cla: yes, documentation)

742 [image_picker]Fixed losing transparency of PNGs (bugfix, cla: yes, submit queue)

790 [cloud_firestore]add sample to get specific document (cla: yes, documentation, flutterfire, submit queue)

793 [video_player]Do not divide by zero (bugfix, cla: yes, submit queue)

815 [google_maps_flutter] adds support for custom icon from a byte array (PNG) (cla: yes, feature, needs love)