CrOS Media App: Add isDevChannel to window.features.

Feeds in isDevChannel to window.features via loadTimeData. This allows
us to determine if the SWA is running in a DEV channel.

Bug: b/159267911
Change-Id: Id4dcbb8be14fc726cf995d9accba07658f55ef88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2531336
Commit-Queue: David Lei <dlei@google.com>
Reviewed-by: David Lei <dlei@google.com>
Reviewed-by: Patti <patricialor@chromium.org>
Auto-Submit: David Lei <dlei@google.com>
Cr-Commit-Position: refs/heads/master@{#826597}

chrome/browser/chromeos/web_applications/chrome_media_app_ui_delegate.cc

@@ -47,4 +47,5 @@ void ChromeMediaAppUIDelegate::PopulateLoadTimeData(
   version_info::Channel channel = chrome::GetChannel();
   source->AddBoolean("flagsMenu", channel != version_info::Channel::BETA &&
                                       channel != version_info::Channel::STABLE);
+  source->AddBoolean("isDevChannel", channel == version_info::Channel::DEV);
 }

chromeos/components/media_app_ui/resources/js/receiver.js

@@ -318,6 +318,7 @@ window.addEventListener('DOMContentLoaded', () => {
   /** @type{{features: Object<string, boolean>}} */ (window).features = {
     imageAnnotation: loadTimeData.getBoolean('imageAnnotation'),
     flagsMenu: loadTimeData.getBoolean('flagsMenu'),
+    isDevChannel: loadTimeData.getBoolean('isDevChannel'),
   };
 
   const app = getApp();