[chromecast] add an UNMANAGED_APP layer.

Bug: internal b/112687577
Test: x86
Change-Id: Id6bab442b6c56cef97f91e71a8ec34cfb0f8368e
Reviewed-on: https://chromium-review.googlesource.com/1177887
Commit-Queue: Gaofeng Huang <gfhuang@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583773}

chromecast/browser/cast_web_view.h

@@ -101,6 +101,9 @@ class CastWebView {
     // True if this CastWebView is for running a remote control app.
     bool is_remote_control_mode = false;
 
+    // Whether this CastWebView should be managed by web ui window manager.
+    bool managed = true;
+
     CreateParams();
   };
 

chromecast/graphics/cast_window_manager.h

@@ -27,7 +27,10 @@ class CastWindowManager {
   // Note: these window IDs are ordered by z-order.
   enum WindowId {
     BOTTOM = -1,
+    // Base layer for WebUiManager and apps and activities managed by it.
     APP = BOTTOM,
+    // Apps running in this layer won't be managed by WebUiManager.
+    UNMANAGED_APP,
     DEBUG_OVERLAY,
     INFO_OVERLAY,
     SOFT_KEYBOARD,