Add aconfig flag for media refactor.

Flag: ACONFIG media_controls_refactor DISABLED
Bug: 326408371
Test: atest SystemUITests
Change-Id: I81899c405dc25014fbaf80c8514067638e17d461
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index ba77380..cb6894e 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -563,3 +563,10 @@
         purpose: PURPOSE_BUGFIX
     }
 }
+
+flag {
+    name: "media_controls_refactor"
+    namespace: "systemui"
+    description: "Refactors media code to follow the recommended architecture"
+    bug: "326408371"
+}