Part of #117844

This is a case where we may want to build more instance-tracking functionality into Pigeon itself before doing a conversion, since we currently use per-instance channels. This is now implemented.

Progress

• google_maps_flutter_android
  • Convert inspector calls
  • Convert Dart->Host calls at the method level
  • Convert data objects passed in method calls (can be done incrementally)
    • PlatformCameraUpdate
    • PlatformCircle
    • PlatformHeatmap
    • PlatformMarker
    • PlatformPolygon
    • PlatformPolyline
    • PlatformTileOverlay
  • Convert Host->Dart calls - [google_maps_flutter] Moves Java->Dart calls to Pigeon packages#7040
  • Convert platform view creation params (blocked on [pigeon] Make the codec public #150631) - [google_maps_flutter] Converts map configuration and platform view creation params to Pigeon packages#7207
• google_maps_flutter_ios
  • Convert inspector calls - [google_maps_flutter] Move iOS inspector to Pigeon packages#6937
  • Convert Dart->Host calls at the method level - [google_maps_flutter] Semi-convert remaining iOS host API calls to Pigeon packages#7079
  • Convert data objects passed in method calls (can be done incrementally, and the Dart portion of the Android conversions of these classes can be re-used modulo any platform-SDK-specific differences)
    • PlatformCameraUpdate
    • PlatformCircle
    • PlatformHeatmap
    • PlatformMarker
    • PlatformPolygon
    • PlatformPolyline
    • PlatformTileOverlay
  • Convert Host->Dart calls - [google_maps_flutter] Convert Obj-C->Dart calls to Pigeon packages#7086
  • Convert platform view creation params (blocked on [pigeon] Make the codec public #150631) - [google_maps_flutter] Converts map configuration and platform view creation params to Pigeon packages#7207