Don't count modifiers-changed events as being user gestures.

third_party/WebKit/public/platform/Platform.h

Index: third_party/WebKit/public/platform/Platform.h
diff --git a/third_party/WebKit/public/platform/Platform.h b/third_party/WebKit/public/platform/Platform.h
index 86c66e5bb294c1272686122a0dbc36e6c92fad1a..f7360bf6cb93be8d78ffe7b66497474390e0ac11 100644
--- a/third_party/WebKit/public/platform/Platform.h
+++ b/third_party/WebKit/public/platform/Platform.h
@@ -626,6 +626,11 @@ class BLINK_PLATFORM_EXPORT Platform {
   // Returns 0 if DOM key enum is not found.
   virtual int DomKeyEnumFromString(const WebString& key_string) { return 0; }
 
+  // This method returns whether the specified |domKey| is a modifier key.
+  // |domKey| values are based on the value defined in
+  // ui/events/keycodes/dom3/dom_key_data.h.
+  virtual bool IsDomKeyForModifier(int dom_key) { return false; }
+
   // Quota -----------------------------------------------------------
 
   // Queries the storage partition's storage usage and quota information.