Move middle-click autoscroll to synthetic fling.

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

Index: third_party/WebKit/Source/core/input/EventHandler.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandler.cpp b/third_party/WebKit/Source/core/input/EventHandler.cpp
index 6b7dbae6315f52828a398c5d4a45c876dbe87ed4..dfc65652a42d212bd4565b4cf473eb755afd4221 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -253,8 +253,8 @@ void EventHandler::StartMiddleClickAutoscroll(LayoutObject* layout_object) {
   if (!controller)
     return;
   controller->StartMiddleClickAutoscroll(
-      ToLayoutBox(layout_object),
-      mouse_event_manager_->LastKnownMousePosition());
+      layout_object->GetFrame(), mouse_event_manager_->LastKnownMousePosition(),
+      mouse_event_manager_->LastKnownMousePositionGlobal());
   mouse_event_manager_->InvalidateClick();
 }
 
@@ -309,6 +309,7 @@ HitTestResult EventHandler::HitTestResultAtPoint(
 }
 
 void EventHandler::StopAutoscroll() {
+  scroll_manager_->StopMiddleClickAutoscroll();
   scroll_manager_->StopAutoscroll();
 }
 
@@ -650,7 +651,7 @@ WebInputEventResult EventHandler::HandleMousePressEvent(
     // return.
     bool is_middle_click_autoscroll_in_progress =
         scroll_manager_->MiddleClickAutoscrollInProgress();
-    scroll_manager_->StopAutoscroll();
+    scroll_manager_->StopMiddleClickAutoscroll();
     if (is_middle_click_autoscroll_in_progress) {
       // We invalidate the click when exiting middle click auto scroll so that
       // we don't inadvertently navigate away from the current page (e.g. the
@@ -805,6 +806,19 @@ WebInputEventResult EventHandler::HandleMouseMoveOrLeaveEvent(
   mouse_event_manager_->CancelFakeMouseMoveEvent();
   mouse_event_manager_->HandleSvgPanIfNeeded(false);
 
+  if (RuntimeEnabledFeatures::MiddleClickAutoscrollEnabled()) {
+    if (Page* page = frame_->GetPage()) {
+      if (mouse_event.GetType() == WebInputEvent::kMouseLeave &&
+          mouse_event.button != WebPointerProperties::Button::kMiddle) {

[bokan, 2017/06/15 17:40:12]

Does this mean that if the cursor leaves the window we'll cancel the auto scroll
if we were in the "toggle" mode but not if we were in the "holding" mode? Is
this the behaviour today?

[aelias_OOO_until_Jul13, 2017/06/15 22:19:54]

Yes, that's the preexisting behavior.

+        page->GetAutoscrollController().StopMiddleClickAutoscroll(frame_);
+      } else {
+        page->GetAutoscrollController().HandleMouseMoveForMiddleClickAutoscroll(
+            frame_, mouse_event_manager_->LastKnownMousePositionGlobal(),
+            mouse_event.button == WebPointerProperties::Button::kMiddle);
+      }
+    }
+  }
+
   if (frame_set_being_resized_) {
     return UpdatePointerTargetAndDispatchEvents(
         EventTypeNames::mousemove, frame_set_being_resized_.Get(), String(),
@@ -936,9 +950,12 @@ WebInputEventResult EventHandler::HandleMouseReleaseEvent(
     frame_->Selection().SetCaretBlinkingSuspended(false);
 
   if (RuntimeEnabledFeatures::MiddleClickAutoscrollEnabled()) {
-    if (Page* page = frame_->GetPage())
+    if (Page* page = frame_->GetPage()) {
       page->GetAutoscrollController()
-          .HandleMouseReleaseForMiddleClickAutoscroll(frame_, mouse_event);
+          .HandleMouseReleaseForMiddleClickAutoscroll(
+              frame_,
+              mouse_event.button == WebPointerProperties::Button::kMiddle);
+    }
   }
 
   mouse_event_manager_->SetMousePressed(false);