Return AltGraph for right-Alt keydown/keyup, under layouts which use AltGraph.

ui/events/keycodes/platform_key_map_win.h

Index: ui/events/keycodes/platform_key_map_win.h
diff --git a/ui/events/keycodes/platform_key_map_win.h b/ui/events/keycodes/platform_key_map_win.h
index 541ab3343f99b93ce89f20a8bae68819d196e163..143152995754b40e0e2187414566c4c29ac9a86f 100644
--- a/ui/events/keycodes/platform_key_map_win.h
+++ b/ui/events/keycodes/platform_key_map_win.h
@@ -44,6 +44,9 @@ class EVENTS_EXPORT PlatformKeyMap {
 
   HKL keyboard_layout_ = 0;
 
+  // True if |keyboard_layout_| makes use of the AltGraph modifier.
+  bool has_alt_graph_ = false;
+
   typedef std::pair<int /*KeyboardCode*/, int /*EventFlags*/>
       KeyboardCodeEventFlagsPair;
   typedef std::unordered_map<KeyboardCodeEventFlagsPair,