hello

third_party/WebKit/Source/core/events/MouseEventInit.idl

Index: third_party/WebKit/Source/core/events/MouseEventInit.idl
diff --git a/third_party/WebKit/Source/core/events/MouseEventInit.idl b/third_party/WebKit/Source/core/events/MouseEventInit.idl
index cbb4d7d83781cf975b530f6450f09681fc714900..20c94eae85452b5f1d2bdabe78a2de4ed4668554 100644
--- a/third_party/WebKit/Source/core/events/MouseEventInit.idl
+++ b/third_party/WebKit/Source/core/events/MouseEventInit.idl
@@ -17,4 +17,10 @@ dictionary MouseEventInit : EventModifierInit {
     // https://dvcs.w3.org/hg/pointerlock/raw-file/default/index.html#extensions-to-the-mouseeventinit-dictionary
     long movementX = 0;
     long movementY = 0;
+
+    // Canvas HitRegion
+    // https://html.spec.whatwg.org/multipage/scripting.html#MouseEvent-partial
+    // TODO(zino): This attribute should be declared as partial dictionary but
+    // IDL parser can't support it yet. Please see: http://crbug.com/579896
+    DOMString? region = null;
 };