Add a flag to update hover effect when a layout is changed

third_party/WebKit/Source/core/input/MouseEventManager.cpp

Index: third_party/WebKit/Source/core/input/MouseEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/MouseEventManager.cpp b/third_party/WebKit/Source/core/input/MouseEventManager.cpp
index e4a1ec7df78bfad490fc49ea7b359e7fa48cdcce..5d9f2b465a39681309c10be8cc00add88f7e823d 100644
--- a/third_party/WebKit/Source/core/input/MouseEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/MouseEventManager.cpp
@@ -56,7 +56,11 @@ String CanvasRegionId(Node* node, const WebMouseEvent& mouse_event) {
 
 // The amount of time to wait before sending a fake mouse event triggered
 // during a scroll.
-const double kFakeMouseMoveInterval = 0.1;
+const double kFakeMouseMoveIntervalDuringScroll = 0.1;
+
+// The amount of time to wait before sending a fake mouse event on style and
+// layout changes sets to 50Hz, same as common screen refresh rate.
+const double kFakeMouseMoveIntervalPerFrame = 0.02;

[dtapuska, 2017/06/28 19:15:17]

I believe constexpr is preferred

[lanwei, 2017/07/04 18:37:15]

Done.

 
 // TODO(crbug.com/653490): Read these values from the OS.
 #if OS(MACOSX)
@@ -581,7 +585,8 @@ void MouseEventManager::SetLastKnownMousePosition(const WebMouseEvent& event) {
   last_known_mouse_global_position_ = event.PositionInScreen();
 }
 
-void MouseEventManager::DispatchFakeMouseMoveEventSoon() {
+void MouseEventManager::DispatchFakeMouseMoveEventSoon(
+    DispatchInterval dispatch_interval) {
   if (mouse_pressed_)

[dtapuska, 2017/06/28 19:15:18]

So if mouse is pressed or cursor isn't known then we don't update the cursor.
This is different than before. Do we need to take these into account?

[lanwei, 2017/07/04 18:37:15]

We should update hover states and mouse cursor when mouse is pressed, but we
cannot update them correctly when the mouse position is unknown. I will fix it
in another patch.

     return;
 
@@ -590,8 +595,12 @@ void MouseEventManager::DispatchFakeMouseMoveEventSoon() {
 
   // Reschedule the timer, to prevent dispatching mouse move events
   // during a scroll. This avoids a potential source of scroll jank.
-  fake_mouse_move_event_timer_.StartOneShot(kFakeMouseMoveInterval,
-                                            BLINK_FROM_HERE);
+  // Or dispatch a fake mouse move to update hover states when the layout
+  // changes.
+  double interval = dispatch_interval == DispatchInterval::kDuringScroll
+                        ? kFakeMouseMoveIntervalDuringScroll
+                        : kFakeMouseMoveIntervalPerFrame;
+  fake_mouse_move_event_timer_.StartOneShot(interval, BLINK_FROM_HERE);
 }
 
 void MouseEventManager::DispatchFakeMouseMoveEventSoonInQuad(
@@ -604,7 +613,7 @@ void MouseEventManager::DispatchFakeMouseMoveEventSoonInQuad(
           view->RootFrameToContents(last_known_mouse_position_)))
     return;
 
-  DispatchFakeMouseMoveEventSoon();
+  DispatchFakeMouseMoveEventSoon(DispatchInterval::kDuringScroll);
 }
 
 WebInputEventResult MouseEventManager::HandleMousePressEvent(
@@ -1097,4 +1106,8 @@ bool MouseEventManager::MouseDownMayStartDrag() {
   return mouse_down_may_start_drag_;
 }
 
+bool MouseEventManager::FakeMouseMovePending() {
+  return fake_mouse_move_event_timer_.IsActive();
+}
+
 }  // namespace blink