Update shade transition on full expand or collapse

On the lockscreen, this is normally done by a call in
LockscreenShadeTransitionController when updating dragDownAmount.
However it seems that sometimes this update doesn't happen, leaving
MediaHierarchyManager in a bad state. This change listens to the
ShadeInteractor as a backup to ensure the state is updated when the
transition has finished.

Bug: 319244625
Flag: com.android.systemui.media_controls_lockscreen_shade_bug_fix
Test: manual - swipe shade while locked and unlocked and landscape mode
Test: manual - same on tablet device
Change-Id: I5c310ab038603c33f0a6a202ebcee9110e0612d9
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 4311e79..6b3ddc7 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -981,6 +981,16 @@
 }
 
 flag {
+  name: "media_controls_lockscreen_shade_bug_fix"
+  namespace: "systemui"
+  description: "Use ShadeInteractor for media location changes"
+  bug: "319244625"
+  metadata {
+    purpose: PURPOSE_BUGFIX
+  }
+}
+
+flag {
   namespace: "systemui"
   name: "enable_view_capture_tracing"
   description: "Enables view capture tracing in System UI."