fix(app_installations,android): dispatch ID-change events on the main thread

[SelaseKay]

Description

FidListener.onFidChanged() is invoked on Firebase's blocking executor. The Android installations plugin was calling EventSink.success() on that background thread, which FlutterJNI rejects (@UiThread).

This posts the event onto the main looper (same pattern as Firestore / Functions / Remote Config stream handlers) and unregisters the FidListenerHandle on cancel.

Reproduced on a Pixel_9a emulator with a fresh install: subscribe to onIdChange, then getId() + getToken() with no delay. Before the fix, logcat showed:

java.lang.RuntimeException: Methods marked with @UiThread must be executed on the main thread. Current thread: Firebase Blocking Thread #0
  at TokenChannelStreamHandler.kt:25

After the fix, getId/getToken complete and onIdChange delivers the FID with no exception.

Related Issues

• Fixes [firebase_app_installations] Android ID-change callback throws on a background thread #18646

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (melos run analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• I signed the CLA.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

[gemini-code-assist]

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize the Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counterproductive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.