Implement Middle Click Autoscroll on all platforms not just Windows

third_party/WebKit/Source/core/page/AutoscrollController.cpp

Index: third_party/WebKit/Source/core/page/AutoscrollController.cpp
diff --git a/third_party/WebKit/Source/core/page/AutoscrollController.cpp b/third_party/WebKit/Source/core/page/AutoscrollController.cpp
index 34620a291a0f193b9ce7d0e5e8744a84ed516de0..78b4379ddd2a2e4bbc16aa2025f79d8bcb43a224 100644
--- a/third_party/WebKit/Source/core/page/AutoscrollController.cpp
+++ b/third_party/WebKit/Source/core/page/AutoscrollController.cpp
@@ -74,7 +74,7 @@ bool AutoscrollController::autoscrollInProgress(const LayoutBox* layoutObject) c
 
 void AutoscrollController::startAutoscrollForSelection(LayoutObject* layoutObject)
 {
-    // We don't want to trigger the autoscroll or the panScroll if it's already active
+    // We don't want to trigger the autoscroll or the middleClickAutoscroll if it's already active
     if (m_autoscrollType != NoAutoscroll)
         return;
     LayoutBox* scrollable = LayoutBox::findAutoscrollable(layoutObject);
@@ -101,14 +101,11 @@ void AutoscrollController::stopAutoscroll()
     if (!scrollable)
         return;
 
-#if OS(WIN)
-    if (panScrollInProgress()) {
+    if (RuntimeEnabledFeatures::middleClickAutoscrollEnabled() && middleClickAutoscrollInProgress()) {
         if (FrameView* view = scrollable->frame()->view()) {
             view->setCursor(pointerCursor());
         }
     }
-#endif
-
     m_autoscrollType = NoAutoscroll;
 }
 
@@ -130,12 +127,12 @@ void AutoscrollController::updateAutoscrollLayoutObject()
 
     LayoutObject* layoutObject = m_autoscrollLayoutObject;
 
-#if OS(WIN)
-    HitTestResult hitTest = layoutObject->frame()->eventHandler().hitTestResultAtPoint(m_panScrollStartPos, HitTestRequest::ReadOnly | HitTestRequest::Active);
+    if (RuntimeEnabledFeatures::middleClickAutoscrollEnabled()) {
+        HitTestResult hitTest = layoutObject->frame()->eventHandler().hitTestResultAtPoint(m_middleClickAutoscrollStartPos, HitTestRequest::ReadOnly | HitTestRequest::Active);
 
-    if (Node* nodeAtPoint = hitTest.innerNode())
-        layoutObject = nodeAtPoint->layoutObject();
-#endif
+        if (Node* nodeAtPoint = hitTest.innerNode())
+            layoutObject = nodeAtPoint->layoutObject();
+    }
 
     while (layoutObject && !(layoutObject->isBox() && toLayoutBox(layoutObject)->canAutoscroll()))
         layoutObject = layoutObject->parent();
@@ -187,7 +184,6 @@ void AutoscrollController::updateDragAndDrop(Node* dropTargetNode, const IntPoin
     }
 }
 
-#if OS(WIN)
 void AutoscrollController::handleMouseReleaseForPanScrolling(LocalFrame* frame, const PlatformMouseEvent& mouseEvent)
 {
     if (!frame->isMainFrame())
@@ -208,29 +204,23 @@ void AutoscrollController::handleMouseReleaseForPanScrolling(LocalFrame* frame,
     }
 }
 
-bool AutoscrollController::panScrollInProgress() const
+bool AutoscrollController::middleClickAutoscrollInProgress() const
 {
     return m_autoscrollType == AutoscrollForPanCanStop || m_autoscrollType == AutoscrollForPan;
 }
 
 void AutoscrollController::startPanScrolling(LayoutBox* scrollable, const IntPoint& lastKnownMousePosition)
 {
-    // We don't want to trigger the autoscroll or the panScroll if it's already active
+    // We don't want to trigger the autoscroll or the middleClickAutoscroll if it's already active
     if (m_autoscrollType != NoAutoscroll)
         return;
 
     m_autoscrollType = AutoscrollForPan;
     m_autoscrollLayoutObject = scrollable;
-    m_panScrollStartPos = lastKnownMousePosition;
+    m_middleClickAutoscrollStartPos = lastKnownMousePosition;
 
     startAutoscroll();
 }
-#else
-bool AutoscrollController::panScrollInProgress() const
-{
-    return false;
-}
-#endif
 
 // FIXME: This would get get better animation fidelity if it used the monotonicFrameBeginTime instead
 // of WTF::currentTime().
@@ -257,18 +247,16 @@ void AutoscrollController::animate(double)
         break;
     case NoAutoscroll:
         break;
-#if OS(WIN)
     case AutoscrollForPanCanStop:
     case AutoscrollForPan:

[bokan, 2016/09/07 16:33:46]

Please add a DCHECK here that the middleClickAutoScroll WebRuntimeFeature is
enabled.

-        if (!panScrollInProgress()) {
+        if (!middleClickAutoscrollInProgress()) {
             stopAutoscroll();
             return;
         }
         if (FrameView* view = m_autoscrollLayoutObject->frame()->view())
             updatePanScrollState(view, eventHandler.lastKnownMousePosition());
-        m_autoscrollLayoutObject->panScroll(m_panScrollStartPos);
+        m_autoscrollLayoutObject->middleClickAutoscroll(m_middleClickAutoscrollStartPos);
         break;
-#endif
     }
     if (m_autoscrollType != NoAutoscroll && m_autoscrollLayoutObject)
         m_page->chromeClient().scheduleAnimation(m_autoscrollLayoutObject->frame()->view());
@@ -279,15 +267,14 @@ void AutoscrollController::startAutoscroll()
     m_page->chromeClient().scheduleAnimation(m_autoscrollLayoutObject->frame()->view());
 }
 
-#if OS(WIN)
 void AutoscrollController::updatePanScrollState(FrameView* view, const IntPoint& lastKnownMousePosition)
 {
     // At the original click location we draw a 4 arrowed icon. Over this icon there won't be any scroll
     // So we don't want to change the cursor over this area
-    bool east = m_panScrollStartPos.x() < (lastKnownMousePosition.x() - noPanScrollRadius);
-    bool west = m_panScrollStartPos.x() > (lastKnownMousePosition.x() + noPanScrollRadius);
-    bool north = m_panScrollStartPos.y() > (lastKnownMousePosition.y() + noPanScrollRadius);
-    bool south = m_panScrollStartPos.y() < (lastKnownMousePosition.y() - noPanScrollRadius);
+    bool east = m_middleClickAutoscrollStartPos.x() < (lastKnownMousePosition.x() - noPanScrollRadius);
+    bool west = m_middleClickAutoscrollStartPos.x() > (lastKnownMousePosition.x() + noPanScrollRadius);
+    bool north = m_middleClickAutoscrollStartPos.y() > (lastKnownMousePosition.y() + noPanScrollRadius);
+    bool south = m_middleClickAutoscrollStartPos.y() < (lastKnownMousePosition.y() - noPanScrollRadius);
 
     if (m_autoscrollType == AutoscrollForPan && (east || west || north || south))
         m_autoscrollType = AutoscrollForPanCanStop;
@@ -314,6 +301,5 @@ void AutoscrollController::updatePanScrollState(FrameView* view, const IntPoint&
         view->setCursor(middlePanningCursor());
     }
 }
-#endif
 
 } // namespace blink