Maintain Diamond (F15) modifier state when rewriting.

chrome/browser/chromeos/events/event_rewriter.h

Index: chrome/browser/chromeos/events/event_rewriter.h
diff --git a/chrome/browser/chromeos/events/event_rewriter.h b/chrome/browser/chromeos/events/event_rewriter.h
index 2baf8f0fbd8f7ed3dd0d19fc9d2bf70b3f6b68b5..284265d29b7a7eb02729f7ac9e53ffa9738141cf 100644
--- a/chrome/browser/chromeos/events/event_rewriter.h
+++ b/chrome/browser/chromeos/events/event_rewriter.h
@@ -179,9 +179,16 @@ class EventRewriter : public ui::EventRewriter {
   const PrefService* pref_service_for_testing_;
 
   // The sticky keys controller is not owned here;
-  // at time of writing it is a singleton in ash::Shell>
+  // at time of writing it is a singleton in ash::Shell.
   ash::StickyKeysController* sticky_keys_controller_;
 
+  // The ChromeOS Diamond key arrives as F15. Since F15 is not a modifier,
+  // we need to track its pressed state explicitly, and apply the selected
+  // modifier flag to key and mouse presses that arrive while F15 is down.
+  // While the Diamond key is down, this holds the corresponding modifier
+  // ui::EventFlags; otherwise it is EF_NONE.
+  int current_diamond_key_modifier_flags_;
+
   DISALLOW_COPY_AND_ASSIGN(EventRewriter);
 };