Support renaming the be channel to main. (#102)

* Support renaming the be channel to main.

This change automatically detects when the main channel pops into
existence and starts using the latest version of it instead. The forward
compatibility will be removed once the channel has been renamed.

Bug: b/270022609

* recompile action

* Add changelog entry for the be -> main rename.

* update todo and rev changelog version

---------

Co-authored-by: Devon Carew <[email protected]>

Author: sortie

CHANGELOG.md

@@ -1,8 +1,10 @@
-## v1.5.1-dev
+## v1.5.1
 
 * No longer test the `setup-dart` action on pre-2.12 SDKs.
 * Upgrade JS interop code to use extension types
   (the new name for inline classes).
+* The upcoming rename of the `be` channel to `main` is now supported with
+  forward compatibility that switches when the rename happens.
 
 ## v1.5.0
 

dist/main.cjs

@@ -51,9 +51,15 @@ void main(List<String> args) async {
       version =
           raw ? 'latest' : (await latestPublishedVersion(channel, flavor));
     } else if (sdk == 'main') {
-      channel = 'be';
-      version =
-          raw ? 'latest' : (await latestPublishedVersion(channel, flavor));
+      // Check for `main` first and fall back to `be`. This handles the channel
+      // rename from `be` to `main` (also tracked as b/299435467).
+      try {
+        channel = 'main';
+        await latestPublishedVersion(channel, flavor);
+      } catch (_) {
+        channel = 'be';
+      }
+      version = 'latest';
     } else {
       version = sdk;