Summary

• move Android NDK provisioning into the main Gradle invocation
• pass the sdkmanager path, Android SDK root, and validated installed NDK versions from flutter_tools to the Flutter Gradle Plugin
• only fall back to the synthetic externalNativeBuild/CMake path when the main invocation cannot satisfy provisioning

Context

This is a draft to explore the single-invocation direction discussed after #183555 and #185439.

The goal here is to keep the cleaner shape of doing the NDK check where AGP has already resolved the actual ndkVersion, while also tightening the behavior around installation and fallback.

Design

• AndroidGradleBuilder now receives AndroidSdk explicitly instead of reading it from globals
• flutter_tools passes:
  • flutter.androidSdkRoot
  • flutter.installedNdkVersions
  • flutter.sdkManagerPath when installation is actually possible
• the plugin now:
  • returns early when the resolved NDK is already installed
  • installs the resolved NDK with sdkmanager --sdk_root=... when possible
  • verifies source.properties after installation
  • falls back to the synthetic CMake path only when the tool-provided path cannot handle the build

Validation

• packages/flutter_tools/test/general.shard/android/android_gradle_builder_test.dart
• packages/flutter_tools/gradle: FlutterPluginUtilsTest
• local benchmarking still shows the same structural improvement as the earlier prototype:
  • no extra printNdkVersion Gradle invocation
  • no unexpected .cxx output in the fast path

Notes

This is still a draft because I want feedback on the shape before turning it into the replacement for the narrower flavored-only reland.