Mark the ET_MOUSE_MOVED created from a pointer grab as synthesized.

ui/aura/env_input_state_controller.cc

Index: ui/aura/env_input_state_controller.cc
diff --git a/ui/aura/env_input_state_controller.cc b/ui/aura/env_input_state_controller.cc
index 7e3b2916174e83790e28939fcaf8af62bde6c631..65e68144dbeebd9ee3fab733b66961d7fc26676a 100644
--- a/ui/aura/env_input_state_controller.cc
+++ b/ui/aura/env_input_state_controller.cc
@@ -9,6 +9,10 @@
 #include "ui/events/event.h"
 #include "ui/gfx/geometry/point.h"
 
+#if defined(USE_X11)
+#include <X11/Xlib.h>
+#endif
+
 namespace aura {
 
 void EnvInputStateController::UpdateStateForMouseEvent(
@@ -29,6 +33,17 @@ void EnvInputStateController::UpdateStateForMouseEvent(
   if (event.type() != ui::ET_MOUSE_CAPTURE_CHANGED &&
       !(event.flags() & ui::EF_IS_SYNTHESIZED)) {
     SetLastMouseLocation(window, event.root_location());
+  } else if (event.type() == ui::ET_MOUSE_MOVED &&
+             (event.flags() & ui::EF_IS_SYNTHESIZED) &&
+             event.HasNativeEvent()) {
+#if defined(USE_X11)
+    // EnterNotify XEvents create synthesized ET_MOUSE_MOVED events from which
+    // we also need to update the mouse location.
+    XEvent* xev = event.native_event();
+    if (xev->type == EnterNotify) {
+      SetLastMouseLocation(window, event.root_location());
+    }
+#endif  // defined(USE_X11)

[sadrul, 2017/07/04 17:16:49]

Can you just set the mouse location without having to look at the native event
type? Alternatively, can you change the condition above in line 33:34 to
something like:

  if (event.type() != CAPTURE_CHANGED &&
      (!synthesized || has_native_event)) {
    SetLastMouseLocation(...);
  }

Add a comment that if an event is triggered by a native event, that probably
means we should actually take that location.

[Kevin McNee, 2017/07/05 13:52:27]

Done.

Although, I think I could've worded that comment better. I'll clarify it before
committing.

[Kevin McNee, 2017/07/05 14:08:46]

Done.

   }
 }