Adds ability for pre-target accelerators to not consume events

services/ui/public/interfaces/event_matcher.mojom

Index: services/ui/public/interfaces/event_matcher.mojom
diff --git a/services/ui/public/interfaces/event_matcher.mojom b/services/ui/public/interfaces/event_matcher.mojom
index 33e74aa3bae0a20c99395d99cb35b1ef174d2c49..0ef8b50548482633827203c39b70ca3528f0514e 100644
--- a/services/ui/public/interfaces/event_matcher.mojom
+++ b/services/ui/public/interfaces/event_matcher.mojom
@@ -42,6 +42,7 @@ struct EventFlagsMatcher {
 // A matcher to match any key-press event would be:
 // - |type_matcher.type| = ui::mojom::EventType::KEY_PRESSED
 struct EventMatcher {
+  // |accelerator_phase| is only applicable to accelerators.
   // TODO(jamescook): Move this to somewhere accelerator-specific.
   ui.mojom.AcceleratorPhase accelerator_phase;
   EventTypeMatcher? type_matcher;