Fall-back to platform tools in Android SDK detection logic. (#28863)

diff --git a/packages/flutter_tools/lib/src/android/android_sdk.dart b/packages/flutter_tools/lib/src/android/android_sdk.dart
index 72545e0..99bba9f 100644
--- a/packages/flutter_tools/lib/src/android/android_sdk.dart
+++ b/packages/flutter_tools/lib/src/android/android_sdk.dart
@@ -365,6 +365,14 @@
   }
 
   static bool validSdkDirectory(String dir) {
+    return sdkDirectoryHasLicneses(dir) || sdkDirectoryHasPlatformTools(dir);
+  }
+
+  static bool sdkDirectoryHasPlatformTools(String dir) {
+    return fs.isDirectorySync(fs.path.join(dir, 'platform-tools'));
+  }
+
+  static bool sdkDirectoryHasLicneses(String dir) {
     return fs.isDirectorySync(fs.path.join(dir, 'licenses'));
   }