Treat NotifyVirtual events as mouse move events for blink.

ui/events/blink/web_input_event.cc

Index: ui/events/blink/web_input_event.cc
diff --git a/ui/events/blink/web_input_event.cc b/ui/events/blink/web_input_event.cc
index 7b912ae026c85c853fb7fe7316c32acd458d90a5..44714cfb9bf1ea3e3d729101c221e7412aa885b6 100644
--- a/ui/events/blink/web_input_event.cc
+++ b/ui/events/blink/web_input_event.cc
@@ -16,6 +16,10 @@
 #include "ui/events/blink/web_input_event_builders_win.h"
 #endif
 
+#if defined(USE_X11)
+#include "ui/events/x/events_x_utils.h"
+#endif
+
 namespace ui {
 
 namespace {
@@ -388,6 +392,16 @@ blink::WebMouseEvent MakeWebMouseEventFromUiEvent(const MouseEvent& event) {
       click_count = event.GetClickCount();
       break;
     case ET_MOUSE_EXITED: {
+#if defined(USE_X11)
+      // NotifyVirtual events are created for intermediate windows that the
+      // pointer crosses through. These occur when middle clicking.
+      // Change these into mouse move events.
+      const base::NativeEvent& native_event = event.native_event();
+      if (native_event && ui::IsVirtualMouseLeaveEvent(*native_event)) {

[sadrul, 2017/03/15 18:38:14]

Can you just move IsVirtualMouseLeaveEvent() code in here (either a separate
function, or just inline)?

Although, what are the 'intermediate windows' you are referring to?

[sadrul, 2017/03/15 18:48:14]

Also, should we just not generate a EXITED event in this case (i.e. make a
change
https://cs.chromium.org/chromium/src/ui/events/x/events_x_utils.cc?sq=package...)
to return UNKNWON for NotifyVirtual?

[dtapuska, 2017/03/15 19:48:36]

Done.

+        type = blink::WebInputEvent::MouseMove;
+        break;
+      }
+#endif
       static bool s_send_leave =
           base::FeatureList::IsEnabled(features::kSendMouseLeaveEvents);
       type = s_send_leave ? blink::WebInputEvent::MouseLeave