Assign names to VR UI elements for debugging and test.

chrome/browser/android/vr_shell/ui_elements.h

Index: chrome/browser/android/vr_shell/ui_elements.h
diff --git a/chrome/browser/android/vr_shell/ui_elements.h b/chrome/browser/android/vr_shell/ui_elements.h
index 13165341f72c66ab5d3a356e4adf7c9f0da1d7b8..c10c7f1782370a7550f356ffbe0dd5830c6f24e4 100644
--- a/chrome/browser/android/vr_shell/ui_elements.h
+++ b/chrome/browser/android/vr_shell/ui_elements.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_H_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "base/macros.h"
@@ -99,6 +100,9 @@ struct ContentRectangle : public WorldRectangle {
   // Valid IDs are non-negative.
   int id = -1;
 
+  // Name string for debugging and testing purposes.
+  std::string name;
+
   // If a non-negative parent ID is specified, applicable transformations
   // are applied relative to the parent, rather than absolutely.
   int parent_id = -1;