Mark the ET_MOUSE_MOVED created from a pointer grab as synthesized.

ui/aura/env_input_state_controller.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/env_input_state_controller.h"
 
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/env.h"
 #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(
     const Window* window,
     const ui::MouseEvent& event) {
   switch (event.type()) {
     case ui::ET_MOUSE_PRESSED:
       Env::GetInstance()->set_mouse_button_flags(event.button_flags());
       break;
     case ui::ET_MOUSE_RELEASED:
       Env::GetInstance()->set_mouse_button_flags(
           event.button_flags() & ~event.changed_button_flags());
       break;
     default:
       break;
   }
 
   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.

   }
 }
 
 void EnvInputStateController::UpdateStateForTouchEvent(
     const ui::TouchEvent& event) {
   switch (event.type()) {
     case ui::ET_TOUCH_PRESSED:
       touch_ids_down_ |= (1 << event.pointer_details().id);
       Env::GetInstance()->set_touch_down(touch_ids_down_ != 0);
       break;
@@ skipping 31 matching lines @@
   if (client) {
     gfx::Point location_in_screen = location_in_root;
     client->ConvertPointToScreen(root_window, &location_in_screen);
     Env::GetInstance()->set_last_mouse_location(location_in_screen);
   } else {
     Env::GetInstance()->set_last_mouse_location(location_in_root);
   }
 }
 
 }  // namespace aura