Add WindowId to Source on ChromeOS

This change adds support to allow ChromeOS capturers to also pass a
WindowId with a source. This WindowID can be used to help allow plumbing
and passing an Id that the capturing process knows about, in case it
wants to use any in-process capturing logic.

Bug: chromium:1273189
Change-Id: Ibcf494a75aec06eb1c44e6ff5fbdd9e2952e9b7e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/267086
Auto-Submit: Alexander Cooper <alcooper@chromium.org>
Reviewed-by: Mark Foltz <mfoltz@chromium.org>
Commit-Queue: Mark Foltz <mfoltz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#38238}
diff --git a/modules/desktop_capture/desktop_capturer.h b/modules/desktop_capture/desktop_capturer.h
index 2dd0edc..513bf50 100644
--- a/modules/desktop_capture/desktop_capturer.h
+++ b/modules/desktop_capture/desktop_capturer.h
@@ -81,6 +81,11 @@
     // Title of the window or screen in UTF-8 encoding, maybe empty. This field
     // should not be used to identify a source.
     std::string title;
+
+#if defined(CHROMEOS)
+    // TODO(https://crbug.com/1369162): Remove or refactor this value.
+    WindowId in_process_id = kNullWindowId;
+#endif
   };
 
   typedef std::vector<Source> SourceList;