Add id properties to PointerEvent

content/common/input/synthetic_web_input_event_builders.cc

Index: content/common/input/synthetic_web_input_event_builders.cc
diff --git a/content/common/input/synthetic_web_input_event_builders.cc b/content/common/input/synthetic_web_input_event_builders.cc
index 5efaf54d18ea3e192fff74f7cdd7316ddc170494..b949108174993e0b7517abd29d28c051b4556426 100644
--- a/content/common/input/synthetic_web_input_event_builders.cc
+++ b/content/common/input/synthetic_web_input_event_builders.cc
@@ -7,6 +7,7 @@
 #include "base/logging.h"
 #include "content/common/input/web_touch_event_traits.h"
 #include "ui/events/base_event_utils.h"
+#include "ui/events/event.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
 namespace content {
@@ -40,6 +41,7 @@ WebMouseEvent SyntheticWebMouseEventBuilder::Build(
   result.windowY = window_y;
   result.setModifiers(modifiers);
   result.pointerType = pointer_type;
+  result.id = ui::PointerEvent::kMousePointerId;
   return result;
 }